input: Write a python function to create a Flask application with logging set up to output to stdout.
  assert app.logger.level == logging.DEBUG
  assert app.logger.hasHandlers()
output: import logging
  from flask import Flask
  
  def create_app():
      app = Flask(__name__)
      
      handler = logging.StreamHandler()
      handler.setLevel(logging.DEBUG)
      app.logger.addHandler(handler)
      app.logger.setLevel(logging.DEBUG)
      
      return app
  
  app = create_app()