input: from typing import List
  
  def create_virtual_assistant(project_id: str, session_id: str, language_code: str) -> None:
      """Create a virtual assistant that uses Dialogflow to answer a basic set of questions.
      It continuously prompts the user for input, sends the input to Dialogflow, and outputs
      the response from the assistant.
      
      >>> create_virtual_assistant('project-id', 'session-id', 'en-US')
      User: What is the weather today?
      Assistant: It seems to be sunny today.
      User: Who won the last World Series?
      Assistant: The last World Series was won by the Washington Nationals.
      User: exit
      (Program exits)
      """
output:     import dialogflow_v2 as dialogflow
      import os
  
      os.environ["GOOGLE_APPLICATION_CREDENTIALS"] = "path/to/your/service-account-file.json"
  
      session_client = dialogflow.SessionsClient()
      session = session_client.session_path(project_id, session_id)
  
      while True:
          user_input = input("User: ")
          if user_input.lower() == "exit":
              break
  
          text_input = dialogflow.types.TextInput(text=user_input, language_code=language_code)
          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}")