def string_checker(question, valid_ans=("yes", "no")):
    while True:


        user_response = input(question).lower()

        for item in valid_ans:
            if item == user_response:
                return item

            elif user_response == item[0]:
                return item

def instructions():
    """prints instructions"""

    print("""
*** Instructions ***
    
To begin, choose the number of rounds (or infinite mode).

Then play against the computer, with either R (rock), P 
(paper), or S (scissors).

The rules are as follows:

Paper beats rock
Rock beats scissors
Scissors beats paper

Win the majority of rounds to win overall!
    """)

#main routine
print()
print("Rock Paper Scissors Game!")
print()

#ask the user if they want to see the instructions
want_instructions = string_checker("Do you want to see the instructions? ")

#Display the instructions if the user responded with yes
if want_instructions == 'yes':
    instructions()

print()
print("Program continues")