I have a quick question about an assignment with python, I am using data validation to validate that the user input does not go above a set amount, but I am not sure how to pass the variable by reference. Here is the code # Theater Seating Lab # Abisai Saavedra # the main function def main():     # constants     COST_A = 20     COST_B = 15     COST_C = 10     A = 300     B = 500     C = 200     programIntro(COST_A,COST_B,COST_C,A,B,C)     keepGoing = False     while (keepGoing == False):         totalA,totalB,totalC = get_section ()         display_output(totalA,totalB,totalC)         keepGoing = get_yes_or_no("Are you finished inputting ticket sales? Type yes or no:")     print("Thank you for using the program, program terminating")     # brief explanation of program def programIntro(COST_A,COST_B,COST_C,A,B,C):     print("Hello, welcome to Seatings Calculator")     print("Please follow the system prompts to place number of tickets sold per section")     print("After giving the program the proper information, you will get a total of revenue earned.")     print("----------------------------")     print("Prices:")     print(" o Section A Seatings = $", COST_A,"-" ,A, "MAX seats")     print(" o Section B Seatings = $", COST_B,"-" ,B, "MAX seats")     print(" o Section C Seatings = $", COST_C,"-" ,C, "MAX seats")     print("----------------------------") # gathers information submitted by user def get_section ():    soldA = get_valid_nbr("How many seats were sold in section A")      soldB = get_valid_nbr("How many seats were sold in section B")    soldC = get_valid_nbr("How many seats were sold in section C")    return soldA,soldB,soldC def display_output(totalA,totalB,totalC):     if totalA > 0:         print("you have sold", totalA * 20, "worth of seats in section A by selling", totalA)     if totalB > 0:         print("you have sold", totalB * 15, "worth of seats in section B by selling", totalB)     if totalC > 0:         print("you have sold", totalC * 10, "worth of seats in section C by selling", totalC) # function that validates user input def get_yes_or_no(message):     while True:         new_value = get_string(message).lower()         if new_value == "y" or new_value == "yes":             return True         if new_value == "n" or new_value == "no":             return False         print('Error: invalid value entered')     # function that validates user int input         def get_valid_nbr(message):     new_value = get_integer(message)     while is_invalid(new_value):         new_value = get_integer("Please enter a number greater than 0")     return new_value  # function that returns True or False  def is_invalid(new_value):     if new_value > 300:         print("Theater seatings sold cannot be {0}, it must be lesser than or equal to 300".format(new_value))         return True     if new_value > 500:         print("Theater seatings sold cannot be {0}, it must be lesser than or equal to 500".format(new_value))         return True     if new_value > 200:         print("Theater seatings sold cannot be {0}, it must be lesser than or equal to 200".format(new_value))         return True     if new_value > 0:         return False # validation for input def get_integer(message):     while True:         try:             new_value = int(input(message))             return new_value         except ValueError:             print('  Error: non-integer value entered') def get_string(message):     while True:         new_value = input(message)         if new_value and new_value.strip():             return new_value         else:             print('  Error: no data entered')               # calls main if __name__ == '__main__':     main()

I have a quick question about an assignment with python, I am using data validation to validate that the user input does not go above a set amount, but I am not sure how to pass the variable by reference. Here is the code

# Theater Seating Lab
# Abisai Saavedra

# the main function
def main():
    # constants
    COST_A = 20
    COST_B = 15
    COST_C = 10
    A = 300
    B = 500
    C = 200
    programIntro(COST_A,COST_B,COST_C,A,B,C)
    keepGoing = False
    while (keepGoing == False):
        totalA,totalB,totalC = get_section ()
        display_output(totalA,totalB,totalC)
        keepGoing = get_yes_or_no("Are you finished inputting ticket sales? Type yes or no:")
    print("Thank you for using the program, program terminating")

    # brief explanation of program
def programIntro(COST_A,COST_B,COST_C,A,B,C):

    print("Hello, welcome to Seatings Calculator")
    print("Please follow the system prompts to place number of tickets sold per section")
    print("After giving the program the proper information, you will get a total of revenue earned.")
    print("----------------------------")
    print("Prices:")
    print(" o Section A Seatings = $", COST_A,"-" ,A, "MAX seats")
    print(" o Section B Seatings = $", COST_B,"-" ,B, "MAX seats")
    print(" o Section C Seatings = $", COST_C,"-" ,C, "MAX seats")
    print("----------------------------")

# gathers information submitted by user
def get_section ():
   soldA = get_valid_nbr("How many seats were sold in section A")  
   soldB = get_valid_nbr("How many seats were sold in section B")
   soldC = get_valid_nbr("How many seats were sold in section C")

   return soldA,soldB,soldC

def display_output(totalA,totalB,totalC):
    if totalA > 0:
        print("you have sold", totalA * 20, "worth of seats in section A by selling", totalA)
    if totalB > 0:
        print("you have sold", totalB * 15, "worth of seats in section B by selling", totalB)
    if totalC > 0:
        print("you have sold", totalC * 10, "worth of seats in section C by selling", totalC)

# function that validates user input
def get_yes_or_no(message):
    while True:
        new_value = get_string(message).lower()
        if new_value == "y" or new_value == "yes":
            return True
        if new_value == "n" or new_value == "no":
            return False
        print('Error: invalid value entered')   

 # function that validates user int input        
def get_valid_nbr(message):
    new_value = get_integer(message)
    while is_invalid(new_value):
        new_value = get_integer("Please enter a number greater than 0")

    return new_value

 # function that returns True or False 
def is_invalid(new_value):
    if new_value > 300:
        print("Theater seatings sold cannot be {0}, it must be lesser than or equal to 300".format(new_value))
        return True
    if new_value > 500:
        print("Theater seatings sold cannot be {0}, it must be lesser than or equal to 500".format(new_value))
        return True
    if new_value > 200:
        print("Theater seatings sold cannot be {0}, it must be lesser than or equal to 200".format(new_value))
        return True
    if new_value > 0:
        return False

# validation for input
def get_integer(message):
    while True:
        try:
            new_value = int(input(message))
            return new_value
        except ValueError:
            print('  Error: non-integer value entered')

def get_string(message):
    while True:
        new_value = input(message)
        if new_value and new_value.strip():
            return new_value
        else:
            print('  Error: no data entered') 

        
# calls main
if __name__ == '__main__':
    main()