Python local variable referenced before assignment

I am trying to figure out what I continue to do wrong here with my code. I have tried changing the second portion by eliminating everything after # The main function. Thoughts?

I get the following error

Traceback (most recent call last): File "file", line 1, in import petspgm File "file", line 39, in main() File "file", line 34, in main print('Pet Name: ', pets.get_pet_name) builtins.UnboundLocalError: local variable 'pets' referenced before assignment –

import petspgm

def main():
    #Get a list of pet objects.
    pets = make_list()

    #Display the data in the list.
    print('Here is the data you entered: ')
    display_list(pets)

#This function gets data from the user for 3 pets. It returns a list of pet
#objects containing the data.
def make_list():
    #Create an
    pet_list = []

    #Add three pet objects to the list
    print('Enter the data for 3 pets.')
    for count in range(1, 3):
        #Get the pet data
        print("Pet number " + str(count) + ":")
        pet_name = input("Enter your pet's name: ")
        pet_type = input("Enter the type of pet: ")
        pet_age = float(input("Enter the pet's age: "))

        #Create a new PetData object in memory and assign it to the pet variable.
        pet = petspgm.PetData(pet_name, pet_type, pet_age)

        #Add the object to the list.
        pet_list.append(pet)

        #Return the list.
        return pet_list

#This function accepts a list containing PetData objects as an argument and 

def pet_list():

    #displays the data stored in each object.
    display_list(pet_list)
    for item in pet_list:
        print("Pet's name is: " + item.get_pet_name())
        print("Pet's type is : " + item.get_pet_type())
        print("Pet's age is : " + item.get_pet__age())

#Call the main function
main()

Here is the other half to the code:

class PetData(object):
    def __init__(self, name, animal_type, age):
        self.__pet_name = pet_name
        self.__pet_type = pet_type
        self.__pet_age = pet_age

    def set_name(self, name):
        self.__pet_name = pet_name

    def set_type(self, animal_type):
        self.__pet_type = pet_type

    def set_age(self, age):
        self.__pet_age = pet_age

    def get_name(self):
        return self.__pet_name

    def get_animal_type(self):
        return self.__pet_type

    def get_age(self):
        return self.__pet_age


# The main function
def main():
    # Prompt user to enter name, type, and age of pet
    name = input('What is the name of the pet: ')
    animal_type = input('What type of pet is it: ')
    age = int(input('How old is your pet: '))
    print('This will be added to the records. ')
    print('Here is the data you entered:')
    print('Pet Name: ', pets.get_pet_name)
    print('Animal Type: ', pets.get_pet_type)
    print('Age: ', pets.get_pet_age)
    pets = Pet(name, animal_type, age)

main()