code: def merge_accumulators(self, accumulators):
      return functools.reduce(list.__add__, accumulators)
  
imports: import functools
  from absl.testing import absltest
  import apache_beam
  from apache_beam.testing import util
  from tensorflow_model_analysis.api import types
  from tensorflow_model_analysis.evaluators import confidence_intervals_util
  from tensorflow_model_analysis.evaluators import jackknife
  from tensorflow_model_analysis.metrics import binary_confusion_matrices
  from tensorflow_model_analysis.metrics import metric_types
label_desc: Use image node_id 4 for calling the ListCombineFn obj's underlying member method code with example usage: obj.merge_accumulators(accumulators) and returns: functools