title: Flask application inside Jupyter Notebook
body: <p>I'm trying to access a simple "Hello World" application inside a Jupyter notebook and I'm facing some problems. When I try to access my application by browser I'm getting: This site can’t be reached. If I try the same application from outside notebook everything works. Is there any configuration that I need to make inside Jupyter?</p>
  
  <pre><code>from flask import Flask
  app = Flask(__name__)
  
  @app.route("/")
  def hello(): return "Hello World"
  
  if __name__ == "__main__":
    app.debug = True
    app.run(host='0.0.0.0',port=5005)
   * Running on http://0.0.0.0:5005/ (Press CTRL+C to quit)
  </code></pre>
  
  <p>Getting error log:</p>
  
  <pre><code> File "zmq/backend/cython/checkrc.pxd", line 25, in zmq.backend.cython.checkrc._check_rc
      raise ZMQError(errno)
  ZMQError: Address already in use
  </code></pre>