old_contents: from flask import Flask
  
  
  app = Flask(__name__)
  
  
  @app.route('/')
  def home():
      return 'Hello, world.'
  
new_contents: from flask import Flask
  
  
  app = Flask('ganttchart.web')
  
  
  @app.route('/')
  def home():
      return 'Hello, world.'
  
subject: Change flask module name