old_contents: '''
   Author      : DORIAN JAVA BROWN
   Version     : N/A
   Copyright   : All Rights Reserve; You may use, distribute and modify this code.
   Description : This is a simple calculator that can add, subtract, multiply and divide using functions 
   '''
  
  # functions definitions
  
  # addition fuction
  def add(x, y):
     return x + y
  
  def subtract(x, y):
     """This function subtracts two numbers"""
     return x - y
  
  def multiply(x, y):
     """This function multiplies two numbers"""
     return x * y
  
  def divide(x, y):
     """This function divides two numbers"""
     return x / y
  
  # take input from the user
  print("Select operation.")
  print("1.Add")
  print("2.Subtract")
  print("3.Multiply")
  print("4.Divide")
  
  choice = input("Enter choice(1/2/3/4):")
  
  num1 = int(input("Enter first number: "))
  num2 = int(input("Enter second number: "))
  
  if choice == '1':
     print(num1,"+",num2,"=", add(num1,num2))
  
  elif choice == '2':
     print(num1,"-",num2,"=", subtract(num1,num2))
  
  elif choice == '3':
     print(num1,"*",num2,"=", multiply(num1,num2))
  
  elif choice == '4':
     print(num1,"/",num2,"=", divide(num1,num2))
  else:
     print("Invalid input")
new_contents: '''
   Author      : DORIAN JAVA BROWN
   Version     : N/A
   Copyright   : All Rights Reserve; You may use, distribute and modify this code.
   Description : This is a simple calculator that can add, subtract, multiply and divide using functions 
   '''
  
  
  
  '''functions definitions'''
  
  # addition function
  def add(x, y):
     return x + y
  
  # subtraction function
  def subtract(x, y):
     return x - y
  
  # multiplication function
  def multiply(x, y):
     return x * y
  
  # divison function
  def divide(x, y):
     return x / y
  
  # operation selection from the user
  print("\t\tSelect operation:")
  print("==============================================")
  print("1.Add")
  print("2.Subtract")
  print("3.Multiply")
  print("4.Divide")
  
  choice = input("Enter choice(1/2/3/4):")
  
  num1 = int(input("Enter first number: "))
  num2 = int(input("Enter second number: "))
  
  if choice == '1':
     print(num1,"+",num2,"=", add(num1,num2))
  
  elif choice == '2':
     print(num1,"-",num2,"=", subtract(num1,num2))
  
  elif choice == '3':
     print(num1,"*",num2,"=", multiply(num1,num2))
  
  elif choice == '4':
     print(num1,"/",num2,"=", divide(num1,num2))
  else:
     print("Invalid input")
subject: Update fix