code: def _compute_partition_count_histogram(
      col, backend: pipeline_backend.PipelineBackend
  ):
      """Computes histogram of counts per partition.
  
      This histogram contains: the number of partitions with total count of
      contributions = 1, 2 etc.
  
      Args:
          col: collection with elements (privacy_id, partition_key).
          backend: PipelineBackend to run operations on the collection.
      Returns:
          1 element collection, which contains the computed hist.Histogram.
      """
  
      col = backend.values(col, "Drop privacy keys")
      # col: (pk)
  
      col = backend.count_per_element(col, "Count per partition")
      # col: (pk, count)
  
      col = backend.values(col, "Drop partition key")
      # col: (count)
  
      return _compute_frequency_histogram(
          col, backend, hist.HistogramType.COUNT_PER_PARTITION
      )
  
imports: import bisect
  import operator
  from typing import List, Tuple
  import numpy
  import pipeline_dp
  from pipeline_dp import pipeline_backend, pipeline_functions
  from pipeline_dp.dataset_histograms import histograms
label_desc: Use image node_id 15 for calling a global function with example usage: _compute_partition_count_histogram(col, backend) and returns: _compute_frequency_histogram