code: def runserver(app=None, reloader=None, debug=None, host=None, port=None):
      
      debug = debug or app.config.get('DEBUG', False)
      reloader = reloader or app.config.get('RELOADER', False)
      host = host or app.config.get('HOST', '127.0.0.1')
      port = port or app.config.get('PORT', 5000)
      app.run(
          use_reloader=reloader,
          debug=debug,
          host=host,
          port=port
      )
docs: Run the Flask development server i.e. app.run()