text: print("Welcome to the calculator program!")
  EXIT_USER_INPUT_OPTION = "EXIT"
  print("Enter " + EXIT_USER_INPUT_OPTION + " after a calculation to end program.")
  user_input_after_calculation = ""
  while EXIT_USER_INPUT_OPTION != user_input_after_calculation:
      first_number = int(input("Enter first number: "))
      second_number = int(input("Enter second number: "))
  
      ADDITION_OPERATION = "+"
      SUBTRACTION_OPERATION = "-"
      MULTIPLICATION_OPERATION = "*"
      DIVISION_OPERATION = "/"
      print("Valid operations include: ")
      print(ADDITION_OPERATION)
      print(SUBTRACTION_OPERATION)
      print(MULTIPLICATION_OPERATION)
      print(DIVISION_OPERATION)
  
      operation = input("Enter an operation: ")
  
      if ADDITION_OPERATION == operation:
          sum_result = first_number + second_number
          print("The sum is: " + str(sum_result))
      elif SUBTRACTION_OPERATION == operation:
          difference_result = first_number - second_number
          print("The difference is: " + str(difference_result))
      elif MULTIPLICATION_OPERATION == operation:
          product_result = first_number * second_number
          print("The product is: " + str(product_result))
      elif DIVISION_OPERATION == operation:
          quotient_result = first_number / second_number
          print("The quotient is: " + str(quotient_result))
      else:
          print('The "' + operation + '" operation is invalid.')
  
      user_input_after_calculation = input("Enter " + EXIT_USER_INPUT_OPTION + " to end program or any other text to perform another calculation.")
  