input: Write a function to create a virtual assistant using Python and Dialogflow that can answer a basic set of questions. The function should take input from the user, send it to Dialogflow for processing, and then return and print the assistant's response. If the provided project ID and session ID are valid, the function should loop indefinitely, waiting for user input in each iteration. If the project ID or session ID are invalid, the function should handle the error gracefully and notify the user.
  assert create_virtual_assistant('project-id', 'session-id')==None
  assert create_virtual_assistant('invalid-project-id', 'session-id')==None
output: def create_virtual_assistant(project_id, session_id):
      try:
          import dialogflow_v2 as dialogflow
          session_client = dialogflow.SessionsClient()
          session = session_client.session_path(project_id, session_id)
          
          while True:
              user_input = input("You: ")
              text_input = dialogflow.types.TextInput(text=user_input, language_code='en')
              query_input = dialogflow.types.QueryInput(text=text_input)
              response = session_client.detect_intent(session=session, query_input=query_input)
              print(f"Assistant: {response.query_result.fulfillment_text}")
      except Exception as e:
          print(f"Error: {e}")