code: def healthz():
      if app.ready:
          return PlainTextResponse("ok")
      return PlainTextResponse(
          "service unavailable",
          status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
      )
  
file_path: cortex/test/apis/realtime/text-generator/app/main.py
imports: import os
  from fastapi import FastAPI, status
  from fastapi.responses import PlainTextResponse
  from pydantic import BaseModel
  from transformers import GPT2Tokenizer, GPT2LMHeadModel
label_desc: Use image node_id 2 for calling a global function with example usage: healthz() and returns: PlainTextResponse, PlainTextResponse