old_contents: def main():
      print ("Hello world!")
  
  if __name__ == '__main__':
      main()
new_contents: def main():
      try:
          fileName = "MengZi_Traditional.md"
          filePath = "../../source/" + fileName
          with open(filePath, 'r') as file:
              for line in file:
                  print line
      except IOError:
          print ("The file (" + filePath + ") does not exist.")
  
  if __name__ == '__main__':
      main()
subject: Read a file from Python