Module 2 Required Coding Activity

[silverdog]

Hi,
My code seems running fine on jupyter notebook,
but when pasted into the Module 2 Required Code Submission gived me error ...
Any hint ?

# [] create list-o-matic
# [] copy and paste in edX assignment page

zoo = ['cat', 'goat', 'cat']

def list_o_matic(animal):
    if animal == "":
        animal = zoo.pop()
        print(animal + " popped from list")
    elif animal in zoo:
        zoo.remove(animal)
        print("1 instance of " + animal + " removed from list")
    else:
        zoo.append(animal)
        print("1 instance of " + animal + " appended from list")

while True:
    if zoo == "":
        break
    else:
        animal_name = input("enter the name of an animal: ")
        if animal_name.lower().startswith("q"):
            break
        else:
            list_o_matic(animal_name)
            print(zoo)

print("goodbye")