# 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 following list: {valid_ans}"

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


# Displays instructions

def instruction():
    print('''

**** Instructions ****

To begin, choose the number of rounds (or infinite mode).

Then, play against the computer.  You need 
P (paper) or S (scissors).

The rules are as follows:
o  Paper beats rock
o  Rock beats scissors
o  Scissors beats paper 



Good Luck!
''')


# Main routine
print()
print("💎📄✂️ Rock / Paper / Scissors Game ✂️📄💎")
print()

# ask user if they want to see the instructions and display them if requested
want_instructions = string_checker("Do you want to read the instructions? ")

# checks users enter yes (y) or no (n)
if want_instructions == "yes":
    instruction()

print("program continues")