input: Write a function that creates a virtual assistant using Python and Dialogflow to answer a basic set of questions. The function should take user input, send it to Dialogflow for processing, and print the assistant's response. If the input is empty, the function should print an appropriate message.
  import dialogflow_v2 as dialogflow
  import requests
  
  def virtual_assistant(project_id, session_id):
      session_client = dialogflow.SessionsClient()
      session = session_client.session_path(project_id, session_id)
  
      while True:
          text = input('User: ')
          if not text.strip():
              print('Assistant: Please provide a valid input.')
              continue
          text_input = dialogflow.types.TextInput(text=text, language_code='en-US')
          query_input = dialogflow.types.QueryInput(text=text_input)
          response = session_client.detect_intent(session=session, query_input=query_input)
  
          print('Assistant:', response.query_result.fulfillment_text)
  
  assert virtual_assistant('project-id', 'session-id')=="User: What is your name?\nAssistant: My name is Assistant."
  assert virtual_assistant('project-id', 'session-id')=="User: \nAssistant: Please provide a valid input."
  assert virtual_assistant('project-id', 'session-id')=="User: How are you?\nAssistant: I'm doing well, thank you!"
output: 
  def virtual_assistant(project_id, session_id):
      session_client = dialogflow.SessionsClient()
      session = session_client.session_path(project_id, session_id)
  
      while True:
          text = input('User: ')
          if not text.strip():
              print('Assistant: Please provide a valid input.')
              continue
          text_input = dialogflow.types.TextInput(text=text, language_code='en-US')
          query_input = dialogflow.types.QueryInput(text=text_input)
          response = session_client.detect_intent(session=session, query_input=query_input)
  
          print('Assistant:', response.query_result.fulfillment_text)
  