def yes_no(question):

    to_check = ['yes', 'no']

    valid = False
    while not valid:

        response = input(question).lower()

        for var_item in to_check:
            if response == var_item:
                return response
            elif response == var_item[0]:
                return var_item

        print("Please enter either yes or no\n")


# Loops to make testing faster
for item in range(0, 6):
    want_help = yes_no("Do you want to read the instructions? ")
    print("You said '{}'\n".format(want_help))