# Functions go here
def string_check(question, valid_answers=None, num_letters=3):
    """Checks that users enter the full word or the 'n' letters of a word from a list of valid responses"""

    if valid_answers is None:
        valid_answers = ['encode', 'decode']

    while True:

        response = input(question).lower()

        for item in valid_answers:

            # check if the response is the entire word
            if response == item:
                return item

            # check if it's the first letter
            elif response == item[:num_letters]:
                return item

        print(f"Please choose an option from {valid_answers}")


# Main routine goes here

while True:
    enc_dec = string_check("Encode or decode? ")
    print(f"You chose {enc_dec}")
    print()