old_contents: # -*- coding: utf-8 -*-
  """
  app.py
  flask application that serves webpages
  ---
  Written by Yangwook Ryoo, 2017
  MIT License: see LICENSE at root directory
  """
  from flask import Flask
  app = Flask(__name__)
  
  
  @app.route('/')
  def route_root():
      return 'Hello, WWWWWWWWorld!'
  
new_contents: # -*- coding: utf-8 -*-
  """
  app.py
  flask application that serves webpages
  ---
  Written by Yangwook Ryoo, 2017
  MIT License: see LICENSE at root directory
  """
  from flask import Flask
  app = Flask(__name__)
  
  
  @app.route('/')
  def route_root():
      return 'Hello, World!'
  
subject: revert changed word