input: def create_flask_app(req):
      """
      Create a Flask app that listens for POST requests on the '/webhook' route. When a request is received, extract the necessary parameters from the request and call the 'makeWebhookResult' function to generate a response. The response should be a JSON object containing a 'speech' field with the text to be spoken by the voice assistant. The app should be started on port 5000 and run in debug mode.
      
      Example:
      >>> create_flask_app('{"result": {"action": "productos.sura", "parameters": {"tipo_cliente": "empresas"}}}')
      '{"speech": "Buscando productos para empresas", "displayText": "Buscando productos para empresas", "source": "apiai-onlinestore-shipping"}'
      """
output:     
      from flask import Flask, request, jsonify
      import json
  
      app = Flask(__name__)
  
      @app.route('/webhook', methods=['POST'])
      def webhook():
          req = request.get_json(silent=True, force=True)
          result = req.get("result")
          action = result.get("action")
          parameters = result.get("parameters")
          response = makeWebhookResult(action, parameters)
          return jsonify(response)
  
      def makeWebhookResult(action, parameters):
          if action == "productos.sura":
              tipo_cliente = parameters.get("tipo_cliente")
              speech = f"Buscando productos para {tipo_cliente}"
              return {
                  "speech": speech,
                  "displayText": speech,
                  "source": "apiai-onlinestore-shipping"
              }
          return {}
  
      if __name__ == '__main__':
          app.run(port=5000, debug=True)
  