class_docstr: Performs DP aggregations.
class_docstr_tok: ["Performs","DP","aggregations","."]
docstr: Adds empty accumulators to all `public_partitions` and returns those
  empty accumulators joined with `col`.
docstr_tok: ["Adds","empty","accumulators","to","all","`","public_partitions","`","and","returns","those","empty","accumulators","joined","with","`","col","`","."]
code: def _add_empty_public_partitions(
      self, col, public_partitions, aggregator_fn
  ):
      """Adds empty accumulators to all `public_partitions` and returns those
      empty accumulators joined with `col`."""
      self._add_report_stage(
          "Adding empty partitions for public partitions that are missing in "
          "data"
      )
      public_partitions = self._backend.to_collection(
          public_partitions, col, "Public partitions to collection"
      )
      empty_accumulators = self._backend.map(
          public_partitions,
          lambda partition_key: (partition_key, aggregator_fn([])),
          "Build empty accumulators",
      )
  
      return self._backend.flatten(
          (col, empty_accumulators),
          "Join public partitions with partitions from data",
      )
  
imports: import functools
  from typing import Any, Callable, Optional, Sequence, Tuple, Union
  import pipeline_dp
  from pipeline_dp import budget_accounting
  from pipeline_dp import combiners
  from pipeline_dp import contribution_bounders
  from pipeline_dp import dp_computations
  from pipeline_dp import partition_selection
  from pipeline_dp import pipeline_functions
  from pipeline_dp import report_generator
  from pipeline_dp import sampling_utils
  from pipeline_dp.dataset_histograms import computing_histograms
  from pipeline_dp.private_contribution_bounds import PrivateL0Calculator
label_desc: Use image node_id 13 for calling the DPEngine obj's underlying member method code with example usage: obj._add_empty_public_partitions(col, public_partitions, aggregator_fn) and returns: self