# Check that users have entered a valid
# option based on a list
def string_checker(question, valid_ans):

    while True:

        error = f"Enter either {valid_ans} "

        # get user response and make sure it's lowercase
        user_response = input(question).lower()

        for item in valid_ans:
            # check if the user response is a word in the list
            if item == user_response:
                return item

            # check if the user response is the same as
            # the first letter of an item in the list
            elif user_response == item[0]:
                return item

        print(error)


# Automated testing is below in the form (test_case, expected_value)
yes_no = ['yes', 'no']

# run tests!

user_answer = string_checker("Read instructions? ", yes_no)

print(f'You selected {user_answer}')