updates regex md and adds demo files
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Hey there where ya goin’, not exactly knowin’, who says you have to call just one place home. He’s goin’ everywhere, B.J. McKay and his best friend Bear. He just keeps on movin’, ladies keep improvin’, every day is better than the last. New dreams and better scenes, and best of all I don’t pay property tax. Rollin’ down to Dallas, who’s providin’ my palace, off to New Orleans or who knows where. Places new and ladies, too, I’m B.J. McKay and this is my best friend Bear.
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Ulysses, Ulysses — Soaring through all the galaxies. In search of Earth, flying in to the night. Ulysses, Ulysses — Fighting evil and tyranny, with all his power, and with all of his might. Ulysses — no-one else can do the things you do. Ulysses — like a bolt of thunder from the blue. Ulysses — always fighting all the evil forces bringing peace and justice to all.
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Hong Kong Phooey, number one super guy. Hong Kong Phooey, quicker than the human eye. He’s got style, a groovy style, and a car that just won’t stop. When the going gets tough, he’s really rough, with a Hong Kong Phooey chop (Hi-Ya!). Hong Kong Phooey, number one super guy. Hong Kong Phooey, quicker than the human eye. Hong Kong Phooey, he’s fan-riffic!
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@ -0,0 +1,5 @@
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* I'm a list
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* I'm a second item in the list
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* and a third one
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* me, a 4th one
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File diff suppressed because it is too large
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Aardvark
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Abyssinian
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Adelie Penguin
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Affenpinscher
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Afghan Hound
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African Bush Elephant
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African Civet
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African Clawed Frog
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African Forest Elephant
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African Palm Civet
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African Penguin
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African Tree Toad
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African Wild Dog
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Ainu Dog
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Airedale Terrier
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Akbash
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Akita
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Alaskan Malamute
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Albatross
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Aldabra Giant Tortoise
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Alligator
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Alpine Dachsbracke
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American Bulldog
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American Cocker Spaniel
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American Coonhound
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American Eskimo Dog
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American Foxhound
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American Pit Bull Terrier
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American Staffordshire Terrier
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American Water Spaniel
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Anatolian Shepherd Dog
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Angelfish
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Ant
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Anteater
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Antelope
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Appenzeller Dog
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Arctic Fox
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Arctic Hare
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Arctic Wolf
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Armadillo
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Asian Elephant
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Asian Giant Hornet
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Asian Palm Civet
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Asiatic Black Bear
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Australian Cattle Dog
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Australian Kelpie Dog
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Australian Mist
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Australian Shepherd
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Australian Terrier
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Avocet
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Axolotl
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Aye Aye
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Baboon
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Bactrian Camel
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Badger
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Balinese
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Banded Palm Civet
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Bandicoot
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Barb
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Barn Owl
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Barnacle
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Barracuda
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Basenji Dog
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Basking Shark
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Basset Hound
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Bat
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Bavarian Mountain Hound
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Beagle
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Bear
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Bearded Collie
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Bearded Dragon
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Beaver
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Bedlington Terrier
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Beetle
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Bengal Tiger
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Bernese Mountain Dog
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Bichon Frise
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Binturong
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Bird
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Birds Of Paradise
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Birman
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Bison
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Black Bear
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Black Rhinoceros
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Black Russian Terrier
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Black Widow Spider
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Bloodhound
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Blue Lacy Dog
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Blue Whale
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Bluetick Coonhound
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Bobcat
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Bolognese Dog
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Bombay
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Bongo
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Bonobo
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Booby
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Border Collie
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Border Terrier
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Bornean Orang-utan
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Borneo Elephant
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Boston Terrier
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Bottle Nosed Dolphin
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Boxer Dog
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Boykin Spaniel
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Brazilian Terrier
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Brown Bear
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Budgerigar
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Buffalo
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Bull Mastiff
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Bull Shark
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Bull Terrier
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Bulldog
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Bullfrog
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Bumble Bee
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Burmese
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Burrowing Frog
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Butterfly
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Butterfly Fish
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Caiman
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Caiman Lizard
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Cairn Terrier
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Camel
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Canaan Dog
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Capybara
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Caracal
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Carolina Dog
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Cassowary
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Cat
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Caterpillar
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Catfish
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Cavalier King Charles Spaniel
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Centipede
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Cesky Fousek
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Chameleon
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Chamois
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Cheetah
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Chesapeake Bay Retriever
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Chicken
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Chihuahua
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Chimpanzee
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Chinchilla
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Chinese Crested Dog
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Chinook
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Chinstrap Penguin
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Chipmunk
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Chow Chow
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Cichlid
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Clouded Leopard
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Clown Fish
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Clumber Spaniel
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Coati
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Cockroach
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Collared Peccary
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Collie
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Common Buzzard
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Common Frog
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Common Loon
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Common Toad
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Coral
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Cottontop Tamarin
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Cougar
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Cow
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Coyote
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Crab
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Crab-Eating Macaque
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Crane
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Crested Penguin
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Crocodile
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Cross River Gorilla
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Curly Coated Retriever
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Cuscus
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Cuttlefish
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Dachshund
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Dalmatian
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Darwin's Frog
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Deer
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Desert Tortoise
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Deutsche Bracke
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Dhole
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Dingo
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Discus
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Doberman Pinscher
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Dodo
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Dog
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Dogo Argentino
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Dogue De Bordeaux
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Dolphin
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Donkey
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Dormouse
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Dragonfly
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Drever
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Duck
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Dugong
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Dunker
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Dusky Dolphin
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Dwarf Crocodile
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Eagle
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Earwig
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Eastern Gorilla
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Eastern Lowland Gorilla
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Echidna
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Edible Frog
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Egyptian Mau
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Electric Eel
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Elephant
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Elephant Seal
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Elephant Shrew
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Emperor Penguin
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Emperor Tamarin
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Emu
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English Cocker Spaniel
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English Shepherd
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English Springer Spaniel
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Entlebucher Mountain Dog
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Epagneul Pont Audemer
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Eskimo Dog
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Estrela Mountain Dog
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Falcon
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Fennec Fox
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Ferret
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Field Spaniel
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Fin Whale
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Finnish Spitz
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Fire-Bellied Toad
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Fish
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Fishing Cat
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Flamingo
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Flat Coat Retriever
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Flounder
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Fly
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Flying Squirrel
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Fossa
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Fox
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Fox Terrier
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French Bulldog
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Frigatebird
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Frilled Lizard
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Frog
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Fur Seal
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Galapagos Penguin
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Galapagos Tortoise
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Gar
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Gecko
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Gentoo Penguin
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Geoffroys Tamarin
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Gerbil
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German Pinscher
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German Shepherd
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Gharial
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Giant African Land Snail
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Giant Clam
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Giant Panda Bear
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Giant Schnauzer
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Gibbon
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Gila Monster
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Giraffe
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Glass Lizard
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Glow Worm
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Goat
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Golden Lion Tamarin
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Golden Oriole
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Golden Retriever
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Goose
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Gopher
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Gorilla
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Grasshopper
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Great Dane
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Great White Shark
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Greater Swiss Mountain Dog
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Green Bee-Eater
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Greenland Dog
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Grey Mouse Lemur
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Grey Reef Shark
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Grey Seal
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Greyhound
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Grizzly Bear
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Grouse
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Guinea Fowl
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Guinea Pig
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Guppy
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Hammerhead Shark
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Hamster
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Hare
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Harrier
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Havanese
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Hedgehog
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Hercules Beetle
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Hermit Crab
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Heron
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Highland Cattle
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Himalayan
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Hippopotamus
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Honey Bee
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Horn Shark
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Horned Frog
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Horse
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Horseshoe Crab
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Howler Monkey
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Human
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Humboldt Penguin
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Hummingbird
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Humpback Whale
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Hyena
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Ibis
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Ibizan Hound
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Iguana
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Impala
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Indian Elephant
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Indian Palm Squirrel
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Indian Rhinoceros
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Indian Star Tortoise
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Indochinese Tiger
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Indri
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Insect
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Irish Setter
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Irish WolfHound
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Jack Russel
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Jackal
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Jaguar
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Japanese Chin
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Japanese Macaque
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Javan Rhinoceros
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Javanese
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Jellyfish
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Kakapo
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Kangaroo
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Keel Billed Toucan
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Killer Whale
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King Crab
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King Penguin
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Kingfisher
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Kiwi
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Koala
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Komodo Dragon
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Kudu
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Labradoodle
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Labrador Retriever
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Ladybird
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Leaf-Tailed Gecko
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Lemming
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Lemur
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Leopard
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Leopard Cat
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Leopard Seal
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Leopard Tortoise
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Liger
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Lion
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Lionfish
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Little Penguin
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Lizard
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Llama
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Lobster
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Long-Eared Owl
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Lynx
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Macaroni Penguin
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Macaw
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Magellanic Penguin
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Magpie
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Maine Coon
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Malayan Civet
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Malayan Tiger
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Maltese
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Manatee
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Mandrill
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Manta Ray
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Marine Toad
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Markhor
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Marsh Frog
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Masked Palm Civet
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Mastiff
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Mayfly
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Meerkat
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Millipede
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Minke Whale
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Mole
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Molly
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Mongoose
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Mongrel
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Monitor Lizard
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Monkey
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Monte Iberia Eleuth
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Moorhen
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Moose
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Moray Eel
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Moth
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Mountain Gorilla
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Mountain Lion
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Mouse
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Mule
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Neanderthal
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Neapolitan Mastiff
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Newfoundland
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Newt
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Nightingale
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Norfolk Terrier
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Norwegian Forest
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Numbat
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Nurse Shark
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Ocelot
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Octopus
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Okapi
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Old English Sheepdog
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Olm
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Opossum
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Orang-utan
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Ostrich
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Otter
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Oyster
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Pademelon
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Panther
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Parrot
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Patas Monkey
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Peacock
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Pekingese
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Pelican
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Penguin
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Persian
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Pheasant
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Pied Tamarin
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Pig
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Pika
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Pike
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Pink Fairy Armadillo
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Piranha
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Platypus
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Pointer
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Poison Dart Frog
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Polar Bear
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Pond Skater
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Poodle
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Pool Frog
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Porcupine
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Possum
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Prawn
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Proboscis Monkey
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Puffer Fish
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Puffin
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Pug
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Puma
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Purple Emperor
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Puss Moth
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Pygmy Hippopotamus
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Pygmy Marmoset
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Quail
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Quetzal
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Quokka
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Quoll
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Rabbit
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Raccoon
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Raccoon Dog
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Radiated Tortoise
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Ragdoll
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Rat
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Rattlesnake
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Red Knee Tarantula
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Red Panda
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Red Wolf
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Red-handed Tamarin
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Reindeer
|
||||||
|
Rhinoceros
|
||||||
|
River Dolphin
|
||||||
|
River Turtle
|
||||||
|
Robin
|
||||||
|
Rock Hyrax
|
||||||
|
Rockhopper Penguin
|
||||||
|
Roseate Spoonbill
|
||||||
|
Rottweiler
|
||||||
|
Royal Penguin
|
||||||
|
Russian Blue
|
||||||
|
Sabre-Toothed Tiger
|
||||||
|
Saint Bernard
|
||||||
|
Salamander
|
||||||
|
Sand Lizard
|
||||||
|
Saola
|
||||||
|
Scorpion
|
||||||
|
Scorpion Fish
|
||||||
|
Sea Dragon
|
||||||
|
Sea Lion
|
||||||
|
Sea Otter
|
||||||
|
Sea Slug
|
||||||
|
Sea Squirt
|
||||||
|
Sea Turtle
|
||||||
|
Sea Urchin
|
||||||
|
Seahorse
|
||||||
|
Seal
|
||||||
|
Serval
|
||||||
|
Sheep
|
||||||
|
Shih Tzu
|
||||||
|
Shrimp
|
||||||
|
Siamese
|
||||||
|
Siamese Fighting Fish
|
||||||
|
Siberian
|
||||||
|
Siberian Husky
|
||||||
|
Siberian Tiger
|
||||||
|
Silver Dollar
|
||||||
|
Skunk
|
||||||
|
Sloth
|
||||||
|
Slow Worm
|
||||||
|
Snail
|
||||||
|
Snake
|
||||||
|
Snapping Turtle
|
||||||
|
Snowshoe
|
||||||
|
Snowy Owl
|
||||||
|
Somali
|
||||||
|
South China Tiger
|
||||||
|
Spadefoot Toad
|
||||||
|
Sparrow
|
||||||
|
Spectacled Bear
|
||||||
|
Sperm Whale
|
||||||
|
Spider Monkey
|
||||||
|
Spiny Dogfish
|
||||||
|
Sponge
|
||||||
|
Squid
|
||||||
|
Squirrel
|
||||||
|
Squirrel Monkey
|
||||||
|
Sri Lankan Elephant
|
||||||
|
Staffordshire Bull Terrier
|
||||||
|
Stag Beetle
|
||||||
|
Starfish
|
||||||
|
Stellers Sea Cow
|
||||||
|
Stick Insect
|
||||||
|
Stingray
|
||||||
|
Stoat
|
||||||
|
Striped Rocket Frog
|
||||||
|
Sumatran Elephant
|
||||||
|
Sumatran Orang-utan
|
||||||
|
Sumatran Rhinoceros
|
||||||
|
Sumatran Tiger
|
||||||
|
Sun Bear
|
||||||
|
Swan
|
||||||
|
Tang
|
||||||
|
Tapanuli Orang-utan
|
||||||
|
Tapir
|
||||||
|
Tarsier
|
||||||
|
Tasmanian Devil
|
||||||
|
Tawny Owl
|
||||||
|
Termite
|
||||||
|
Tetra
|
||||||
|
Thorny Devil
|
||||||
|
Tibetan Mastiff
|
||||||
|
Tiffany
|
||||||
|
Tiger
|
||||||
|
Tiger Salamander
|
||||||
|
Tiger Shark
|
||||||
|
Tortoise
|
||||||
|
Toucan
|
||||||
|
Tree Frog
|
||||||
|
Tropicbird
|
||||||
|
Tuatara
|
||||||
|
Turkey
|
||||||
|
Turkish Angora
|
||||||
|
Uakari
|
||||||
|
Uguisu
|
||||||
|
Umbrellabird
|
||||||
|
Vampire Bat
|
||||||
|
Vervet Monkey
|
||||||
|
Vulture
|
||||||
|
Wallaby
|
||||||
|
Walrus
|
||||||
|
Warthog
|
||||||
|
Wasp
|
||||||
|
Water Buffalo
|
||||||
|
Water Dragon
|
||||||
|
Water Vole
|
||||||
|
Weasel
|
||||||
|
Welsh Corgi
|
||||||
|
West Highland Terrier
|
||||||
|
Western Gorilla
|
||||||
|
Western Lowland Gorilla
|
||||||
|
Whale Shark
|
||||||
|
Whippet
|
||||||
|
White Faced Capuchin
|
||||||
|
White Rhinoceros
|
||||||
|
White Tiger
|
||||||
|
Wild Boar
|
||||||
|
Wildebeest
|
||||||
|
Wolf
|
||||||
|
Wolverine
|
||||||
|
Wombat
|
||||||
|
Woodlouse
|
||||||
|
Woodpecker
|
||||||
|
Woolly Mammoth
|
||||||
|
Woolly Monkey
|
||||||
|
Wrasse
|
||||||
|
X-Ray Tetra
|
||||||
|
Yak
|
||||||
|
Yellow-Eyed Penguin
|
||||||
|
Yorkshire Terrier
|
||||||
|
Zebra
|
||||||
|
Zebra Shark
|
||||||
|
Zebu
|
||||||
|
Zonkey
|
||||||
|
Zorse
|
||||||
|
|
@ -41,6 +41,79 @@ One of the advantages of perl regexes is reverse matching.
|
||||||
|
|
||||||
## The basics
|
## The basics
|
||||||
|
|
||||||
|
### Fundamental structure and anchoring
|
||||||
|
|
||||||
|
Download the following [file](./assets/regex_03.txt) which is an American English dictionary we will use to test out some basic patterns.
|
||||||
|
Fire up a terminal and find all words that contain the string `abba`.
|
||||||
|
You already know how to do this with `grep`, nothing really special here.
|
||||||
|
`grep 'abba' regex_03.txt` should give give you a list containing 16 words.
|
||||||
|
Notice the color output in you terminal.
|
||||||
|
|
||||||
|
What if we only want the words containing `abba` but who *also* start with `s`?
|
||||||
|
This can be done with the following line `grep 's.*abba' regex_03.txt`.
|
||||||
|
You should have 6 matches left.
|
||||||
|
How about the same ones, but they have to end with an `s`?
|
||||||
|
You guessed it, `grep 's.*abba.*s' regex_03.txt`, get's the job done.
|
||||||
|
|
||||||
|
Now, what are those special characters?
|
||||||
|
They are *like* [wildcards in bash](https://ryanstutorials.net/linuxtutorial/wildcards.php) but on steroids.
|
||||||
|
In the example above, the `.` represents almost any character, and the `*` means as **many** times as we want.
|
||||||
|
They are both very powerful, and broad, matching patterns that are part of the [fundamental structure](https://www.gnu.org/software/grep/manual/html_node/Fundamental-Structure.html#Fundamental-Structure) of regex.
|
||||||
|
They work well but sometime we need to be a bit more precise, which we'll get to in a bit.
|
||||||
|
|
||||||
|
Second little example with the same list.
|
||||||
|
What if we want all words with the letter `a` in them?
|
||||||
|
Easy, `grep 'a' regex_03.txt` should do the trick but 52849 results are a bit much.
|
||||||
|
Let's trim it back to only the words having `aa` in them?
|
||||||
|
`grep 'aa' regex_03.txt` brings it down to 65 matches.
|
||||||
|
Nice.
|
||||||
|
Now, how about only the ones that *start* with `aa`?
|
||||||
|
This can be done with an other core concept of regex called [anchoring](https://www.gnu.org/software/grep/manual/html_node/Anchoring.html#Anchoring) and can be done as such `grep '^aa' regex_03.txt`.
|
||||||
|
Here the `^` signifies the **start** of the line.
|
||||||
|
Last one, I promise, what if we want of those three only the ones with `s` at the end?
|
||||||
|
Right, `grep '^aa.*s$' regex_03.txt` should do the trick where `$` means **ends** with.
|
||||||
|
|
||||||
|
### Character classes and bracket expansion
|
||||||
|
|
||||||
|
Let's find, in the following [file](./assets/regex_04.txt) all words starting with a capital case letter.
|
||||||
|
This can be done in multiple ways.
|
||||||
|
First we try one you *should* remember from your bandit days.
|
||||||
|
Does `[a-zA-Z]` ring a bell?
|
||||||
|
You used it to do ROT13 rotation somewhere around level 12.
|
||||||
|
`grep '^[A-Z].*' regex_04.txt` greps out all words starting with a capital.
|
||||||
|
Wonderful, but a bit too many words.
|
||||||
|
|
||||||
|
Let's limit it to only words that have punctuation in them.
|
||||||
|
This, `grep '^[A-Z][[:alnum:]]*[[:punct:]].*' regex_04.txt`, which is *very* cryptic does the job.
|
||||||
|
|
||||||
|
Let's break it down a bit:
|
||||||
|
|
||||||
|
* `^[A-Z]` matches all capital letters
|
||||||
|
* `[[:alnum:]]*` all letters and number, as many times as we want
|
||||||
|
* `[[:punct:]]` matches any punctuation, but just **once**
|
||||||
|
* `.*` matches almost any character as many times as we want
|
||||||
|
|
||||||
|
In the above pattern you see *two* different forms of character classes, the `[A-Z]` and the `[[:alnum:]]`.
|
||||||
|
Worth noting is that you can negate an expansion by putting a `^` inside it as such `grep '^[^A-Z].*' regex_03.txt` (not I used the first list because the animals list has no words starting with a capital letter).
|
||||||
|
This is basically the same as `grep '^[a-z].*' regex_03.txt`.
|
||||||
|
|
||||||
|
### The backslash character and special expressions
|
||||||
|
|
||||||
|
If we want to match only animals that contain multiple words we can use [special expressions](https://www.gnu.org/software/grep/manual/html_node/The-Backslash-Character-and-Special-Expressions.html#The-Backslash-Character-and-Special-Expressions).
|
||||||
|
Have a look at the output of this grep pattern `grep '\s[[:alpha:]]*' regex_04.txt`.
|
||||||
|
Here we notice we can select only parts of the lines too!
|
||||||
|
A handy flag we can add to the `grep` command is `-o` which will only print the part that matches (in red).
|
||||||
|
|
||||||
|
If we only want single words coming out of the search we can do this like so `grep -o '\s[a-zA-Z]*\>' regex_04.txt`.
|
||||||
|
Notice how it starts with an empty space?
|
||||||
|
let's break this one down.
|
||||||
|
|
||||||
|
* `\s` matches whitespace
|
||||||
|
* `[a-zA-Z]*` matches the entire alphabet as many times as we want
|
||||||
|
* `\>` matches the end of the word (not really needed here)
|
||||||
|
|
||||||
|
## Beyond basic
|
||||||
|
|
||||||
TODO
|
TODO
|
||||||
|
|
||||||
## Exercises
|
## Exercises
|
||||||
|
|
@ -49,7 +122,7 @@ Below are some practical exercises and files to go with them.
|
||||||
Use them to test out you grepping skills and as inspiration for personal challenges.
|
Use them to test out you grepping skills and as inspiration for personal challenges.
|
||||||
|
|
||||||
* configuration [file](./assets/sysctl.conf)
|
* configuration [file](./assets/sysctl.conf)
|
||||||
* print only lines with actual configuration settings (ignore comments)
|
* print only lines with actual configuration settings (ignore comments and empty lines)
|
||||||
* css [file](./assets/teddit.css)
|
* css [file](./assets/teddit.css)
|
||||||
* extract all the hex color codes
|
* extract all the hex color codes
|
||||||
* html [file](./assets/teddit.html)
|
* html [file](./assets/teddit.html)
|
||||||
|
|
|
||||||
Loading…
Reference in New Issue