class_docstr: The implementation of InternalWindowProcessFunction for PanedWindowAssigner.
class_docstr_tok: ["The","implementation","of","InternalWindowProcessFunction","for","PanedWindowAssigner","."]
code: def prepare_aggregate_accumulator_for_emit(self, window: W):
      panes = self._window_assigner.split_into_panes(window)
      acc = self._window_aggregator.create_accumulators()
      # null namespace means use heap data views
      self._window_aggregator.set_accumulators(None, acc)
      for pane in panes:
          pane_acc = self._ctx.get_window_accumulators(pane)
          if pane_acc:
              self._window_aggregator.merge(pane, pane_acc)
  
imports: from abc import abstractmethod, ABC
  from typing import Generic, List, Iterable, Dict, Set
  from pyflink.common import Row
  from pyflink.common.constants import MAX_LONG_VALUE
  from pyflink.datastream.state import MapState
  from pyflink.fn_execution.table.window_assigner import WindowAssigner, PanedWindowAssigner, MergingWindowAssigner
  from pyflink.fn_execution.table.window_context import Context, K, W
label_desc: Use image node_id 4 for calling the PanedWindowProcessFunction obj's underlying member method code with example usage: obj.prepare_aggregate_accumulator_for_emit(window) without return types