old_contents: #!/usr/bin/env python
  
  import os
  from flask import Flask
  app = Flask(__name__)
  
  @app.route('/')
  
  def hello():
      return open('index.html').read()
  
  port = os.getenv('VCAP_APP_PORT', '5000')
  
  if __name__ == "__main__":
      app.run(host='0.0.0.0', port=int(port))
  
new_contents: #!/usr/bin/env python
  
  import os
  from flask import Flask
  app = Flask(__name__)
  
  @app.route('/')
  
  def hello():
      return open('index.html').read()
  
  port = os.getenv('PORT', '5000')
  
  if __name__ == "__main__":
      app.run(host='0.0.0.0', port=int(port))
  
subject: Update environment variable name for port to listen on from VCAP_APP_PORT (deprecated) -> PORT