code: def _validate_prompt_template(prompt_template: str):
      if (
          "{context_str}" not in prompt_template
          or "{query_str}" not in prompt_template
      ):
          raise Exception(
              "Provided prompt template is invalid, missing `{context_str}`, `{query_str}`. Please ensure both placeholders are present and try again."
          )
  
imports: import os
  from typing import Optional, Dict
  import openai
  import pandas
  import llama_index
  from langchain.llms import OpenAI
  from llama_index.readers.schema.base import Document
  from llama_index.readers import SimpleWebPageReader
  from llama_index.prompts import PromptTemplate
  from llama_index import ServiceContext, StorageContext, load_index_from_storage
  from llama_index import LLMPredictor, OpenAIEmbedding
  from llama_index.indices.vector_store.base import VectorStore
  from llama_hub.github_repo import GithubClient, GithubRepositoryReader
  from llama_hub.youtube_transcript import YoutubeTranscriptReader, is_youtube_video
  from mindsdb.integrations.libs.base import BaseMLEngine
  from mindsdb.utilities.config import Config
  from mindsdb.utilities.security import is_private_url
  from mindsdb.integrations.handlers.llama_index_handler import config
  from mindsdb.integrations.handlers.llama_index_handler.github_loader_helper import _get_github_token, _get_filter_file_extensions, _get_filter_directories
  from mindsdb.integrations.utilities.handler_utils import get_api_key
label_desc: Use image node_id 1 for calling a global function with example usage: _validate_prompt_template(prompt_template) without return types