class_docstr: A CombineFn wrapper that takes accumulators as add_input elements.
  
  In combination with _AccumulateOnlyCombineFn, this makes it possible to
  operate on a CombineFn's accumulators prior to calling extract input. See the
  _AccumulateOnlyCombineFn docstring for more details.
class_docstr_tok: ["A","CombineFn","wrapper","that","takes","accumulators","as","add_input","elements",".","In","combination","with","_AccumulateOnlyCombineFn",",","this","makes","it","possible","to","operate","on","a","CombineFn","'s","accumulators","prior","to","calling","extract","input",".","See","the","_AccumulateOnlyCombineFn","docstring","for","more","details","."]
code: def add_input(
      self, accumulator: _AccumulatorType, element: _AccumulatorType
  ) -> _AccumulatorType:
      return self._combine_fn.merge_accumulators([accumulator, element])
  
imports: from typing import Optional, Set, Tuple, TypeVar
  import apache_beam
  import numpy
  from tensorflow_model_analysis.api import types
  from tensorflow_model_analysis.evaluators import confidence_intervals_util
  from tensorflow_model_analysis.metrics import metric_types
  from tensorflow_model_analysis.slicer import slicer_lib
  from tensorflow_model_analysis.utils import beam_util
label_desc: Use image node_id 1 for calling the _AccumulatorCombineFn obj's underlying member method code with example usage: obj.add_input(accumulator, element) and returns: self