old_contents: from flask import Flask
  app = Flask(__name__)
  
  @app.route('/')
  def hello():
  	return "Hello World!"
  
  if __name__ == '__main__':
  	app.run()
  
new_contents: from flask import Flask
  app = Flask(__name__)
  
  @app.route('/')
  def hello():
  	return "Hello World!"
  
  @app.route('/<name>')
  def hello_name(name):
  	return "Hello {}!".format(name)
  
  if __name__ == '__main__':
  	app.run()
  
subject: add parameter