input: Write a function to create a virtual assistant using Python and Dialogflow to answer a basic set of questions. The function should continuously prompt the user for input and respond using Dialogflow's response. If the given project_id or session_id is invalid, the function should handle the error gracefully and inform the user.
  
  import dialogflow_v2 as dialogflow
  
  def virtual_assistant():
      project_id = 'project-id'
      session_id = 'session-id'
      try:
          session_client = dialogflow.SessionsClient()
          session = session_client.session_path(project_id, session_id)
      except Exception as e:
          print(f"Error: {e}")
          return
  
      while True:
          text = input('User: ')
          text_input = dialogflow.types.TextInput(text=text, language_code='en-US')
          query_input = dialogflow.types.QueryInput(text=text_input)
          try:
              response = session_client.detect_intent(session=session, query_input=query_input)
              print('Assistant:', response.query_result.fulfillment_text)
          except Exception as e:
              print(f"Error: {e}")
              break
  
  assert virtual_assistant() is None
  assert virtual_assistant() is None
  assert virtual_assistant() is None
  assert virtual_assistant() is None
  assert virtual_assistant() is None
output: def virtual_assistant():
      project_id = 'project-id'
      session_id = 'session-id'
      try:
          session_client = dialogflow.SessionsClient()
          session = session_client.session_path(project_id, session_id)
      except Exception as e:
          print(f"Error: {e}")
          return
  
      while True:
          text = input('User: ')
          text_input = dialogflow.types.TextInput(text=text, language_code='en-US')
          query_input = dialogflow.types.QueryInput(text=text_input)
          try:
              response = session_client.detect_intent(session=session, query_input=query_input)
              print('Assistant:', response.query_result.fulfillment_text)
          except Exception as e:
              print(f"Error: {e}")
              break