# Check that users have entered a valid option based on a list
def string_checker(question, valid_ans=("yes", "no")):

    error = f"Please enter a valid option from the following list: {valid_ans}"

    while True:

          # 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 if user does not enter something valid
          print(error)
          print()



# Main testing routine goes here

answers = ["yes", "no"]

yes_no = string_checker("Yes or no? ")

print("You chose: ", yes_no)