code: def validate_file(string):
      if not string:
          raise argparse.ArgumentTypeError("expected a valid file path")
      return string
  
imports: from __future__ import print_function
  import six
  import argparse
  import os
  from pathlib2 import Path
  from six.moves import input
  from six.moves.urllib.parse import urlparse
  from clearml.backend_api.session import Session
  from clearml.backend_api.session.defs import ENV_HOST
  from clearml.backend_config.defs import LOCAL_CONFIG_FILES, LOCAL_CONFIG_FILE_OVERRIDE_VAR
  from clearml.config import config_obj
  from clearml.utilities.pyhocon import ConfigFactory, ConfigMissingException
label_desc: Use image node_id 1 for calling a global function with example usage: validate_file(string) and returns: string