class_docstr: Storage type of a mapped operator's mapped kwargs.
  
  This is created from ``expand_kwargs(xcom_arg)``.
code: def get_total_map_length(
      self, run_id: str, *, session: Session
  ) -> int:
      if isinstance(self.value, collections.abc.Sized):
          return len(self.value)
      length = self.value.get_task_map_length(run_id, session=session)
      if length is None:
          raise NotFullyPopulated({"expand_kwargs() argument"})
      return length
  
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 2 for calling the ListOfDictsExpandInput obj's underlying member method code with example usage: obj.get_total_map_length(run_id) and returns: length, len