docstr: Apply current transformation group to element.
docstr_tok: ["Apply","current","transformation","group","to","element","."]
code: def __call__(self, elem, group_name=None):
      """Apply current transformation group to element."""
      if self.transform_groups[group_name] is None:
          return elem
      else:
          return super().__call__(elem, group_name=group_name)
  
imports: from collections import defaultdict
  from functools import partial
  from typing import Any, Dict, List, Mapping, Optional, Tuple, Union, Callable, Sequence
  from typing_extensions import Protocol
  from avalanche.benchmarks.utils.transforms import MultiParamCompose, TupleTransform, MultiParamTransform
label_desc: Use image node_id 2 for calling the EmptyTransformGroups obj's underlying member method code with example usage: obj.__call__(elem, group_name) and returns: elem, super