It seems to be a command-line tool to generate passwords based on the url (domain), username and some master password. The tool has a list of animals to add to

It seems to be a command-line tool to generate passwords based on the url (domain), username and some master password. The tool has a list of animals to add to the mix, this is probably all hashed somewhat like so pass_gen(domain, user, master_pass, for_each(animal)). You then see the password you can copy-paste into the password field next to the animal's name. You pick the same favorite animal every time and as such will be able to pick the same password every time.