# checks users enter yes (y) or no (n)
def yes_no(question):
     while True:
        response = input(question).lower()

        # checks user response, question
        # repeats if users don't enter yes / no
        if response == "yes" or response == "y":
            return "yes"
        elif response == "no" or response == "n":
            return "no"
        else:
            print("Please enter yes / no")


def instruction ():
    print('''
    
**** Instructions ****

Do something
and then do something else
etc
    
    ''')

#Checks that users enter an integer
# that is more than 13
def int_check():

    while True:

        error = "Please enter an integer that is 13 or more."

        try:
            response = int(input("Enter an integer: "))

            # checks that the number is more than / equal to 13
            if response < 13:
                print(error)
            else:
                return response

        except ValueError:
            print(error)


# Main routine
print()
print("Roll it 13")
print()

# loop for testing purposes


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

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

print("program continues")
target_score = int_check()