class_docstr: Override loader to pass through kwargs for argcomplete testing
code: def _create_loader(self, argv, aliases, flags, classes):
      loader = KVArgParseConfigLoader(
          argv,
          aliases,
          flags,
          classes=classes,
          log=self.log,
          subcommands=self.subcommands,
      )
      loader._argcomplete_kwargs = self.argcomplete_kwargs  # type: ignore[attr-defined]
      return loader
  
imports: import io
  import os
  import typing
  import pytest
  from traitlets import Unicode
  from traitlets.config.application import Application
  from traitlets.config.configurable import Configurable
  from traitlets.config.loader import KVArgParseConfigLoader
label_desc: Use image node_id 2 for calling the ArgcompleteApp obj's underlying member method code with example usage: obj._create_loader(argv, aliases, flags, classes) and returns: loader