title: Trying to run flask with the following code
body: <pre><code>from flask import Flask
  
  app = Flask(_name_)
  
  @app.route('/')
  def index():
      return '&lt;h1&gt;Hello, world&lt;/h1&gt;'
  </code></pre>
  
  <p>I get this error
  * Serving Flask app "application.py"
   * Environment: production
     WARNING: This is a development server. Do not use it in a production deployment.
     Use a production WSGI server instead.
   * Debug mode: off</p>