I think it works 

I found the read me confusing - and I talked to Alex about this already. 
WHAT WORKS: the program  does this from the data.rb file
Animal:
An animal should have a name.
An animal should have an age.
An animal should have a gender.
An animal should have a species.
An animal can have multiple toys.
Client:
A client should have a name.
A client should have an age.
A client should have a number of pets.
Shelter:
The shelter should have a name.
The shelter should have an address.
The shelter should be able to return all the clients.
The shelter should be able to return all the animals.
The shelter should be able to accept an animal (add to it's list).
The shelter should be able to accept a client (add to it's list).
................
DOES NOT WORK (?) / I dont know what is being asked 
Client:
A client should have a hash of pets (with pet names as keys and animal (object) as values) (????????)
A client should be able to accept a pet and add it to their pets list
A client should be able to give up a pet from their list
Relationships:
The shelter should be able to give a pet to a client (?????????)
The shelter should be able to accept pets from clients(?????)