code: def file_check(files: List) -> None:
      files = map(os.path.basename, files)
      if "requirements.txt" not in files:
          raise UserWarning("requirements.txt not found!")
  
      if "main.py" not in files:
          raise UserWarning(
              "main.py not found! Your main.py should contain app \
              object of type chitra.serve.ModelServer"
          )
  
file_path: chitra/chitra/cli/builder.py
imports: import os
  import shlex
  import subprocess
  from glob import glob
  from pathlib import Path
  from typing import List, Optional
  import typer
  import chitra
label_desc: Use image node_id 2 for calling a global function with example usage: file_check(files) without return types