class_docstr: Stand-in stub for task-group-mapping arguments.
  
  This is very similar to an XComArg, but resolved differently. Declared here
  (instead of in the task group module) to avoid import cycles.
code: def resolve(
      self, context: Context, *, session: Session = NEW_SESSION
  ) -> Any:
      data, _ = self._input.resolve(context, session=session)
      return data[self._key]
  
imports: from __future__ import annotations
  import collections.abc
  import functools
  import operator
  from typing import TYPE_CHECKING, Any, Dict, Iterable, Mapping, NamedTuple, Sequence, Sized, Union
  import attr
  from airflow.utils.mixins import ResolveMixin
  from airflow.utils.session import NEW_SESSION, provide_session
label_desc: Use image node_id 3 for calling the MappedArgument obj's underlying member method code with example usage: obj.resolve(context) and returns: data