input: Write a function named `create_virtual_assistant` that sets up a virtual assistant using Python and Dialogflow to answer a basic set of questions. The function should take a `project_id` and `session_id` as arguments and continuously interact with the user. If the user inputs an exit command, the function should stop.
  assert create_virtual_assistant('project-id', 'session-id')==None
  assert create_virtual_assistant('another-project-id', 'another-session-id')==None
output: def create_virtual_assistant(project_id, session_id):
      import dialogflow_v2 as dialogflow
      session_client = dialogflow.SessionsClient()
      session = session_client.session_path(project_id, session_id)
      
      while True:
          user_input = input("You: ")
          if user_input.lower() in ['exit', 'quit', 'bye']:
              break
          
          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}")