code: def validate_file(self, uri: str) -> None:
      validate_file(uri, self._fs.afs)
  
imports: from typing import Optional, Union, Tuple, List
  import os
  import sys
  from py4j.java_gateway import JavaGateway, GatewayParameters, launch_gateway
  from hail.ir.renderer import CSERenderer
  from hail.ir import finalize_randomness
  from .py4j_backend import Py4JBackend, uninstall_exception_handler
  from .backend import local_jar_information
  from ..expr import Expression
  from ..expr.types import HailType
  from hailtop.utils import find_spark_home
  from hailtop.fs.router_fs import RouterFS
  from hailtop.aiotools.validators import validate_file
label_desc: Use image node_id 2 for calling the LocalBackend obj's underlying member method code with example usage: obj.validate_file(uri) without return types