input: Write a function to implement a simple chatbot using Python and Dialogflow, which can answer questions about the current days of the week. The function should handle requests to the root URL ('/') using both GET and POST methods. It should generate a session ID if not provided and use the Dialogflow API to detect the intent from the text input. Finally, it should return the fulfillment text from the response.
  
  
  from flask import Flask
  from flask_restful import Resource, Api
  from dialogflow import detect_intent_texts
  
  app = Flask(__name__)
  api = Api(app)
  
  @app.route('/', methods=['GET', 'POST'])
  def detect_intent_text():
      if 'session_id' not in request.args:
          session_id = generate_session_id()
      else:
          session_id = request.args['session_id']
      text = request.args['text'] if 'text' in request.args else ''
      request = detect_intent_texts(session_id, text)
      response = request.fulfillment_text
      return response
  
  if __name__ == '__main__':
      app.run()
  
  
  assert detect_intent_text('What day is it?') == 'The current day of the week is...'
  assert detect_intent_text('Today is Friday.', 'session_id_123') == 'Okay, today is Friday.'
  assert detect_intent_text('Which day is today?', '') == 'The current day of the week is...'
  assert detect_intent_text('Tomorrow is Saturday.', 'session_id_456') == 'Sure, tomorrow is Saturday.'
  assert detect_intent_text('', 'session_id_789') == ''
output: def detect_intent_text(text, session_id=None):
      if not session_id:
          session_id = generate_session_id()
      request = detect_intent_texts(session_id, text)
      response = request.fulfillment_text
      return response