class_docstr: The implementation of InternalWindowProcessFunction for MergingWindowAssigner.
class_docstr_tok: ["The","implementation","of","InternalWindowProcessFunction","for","MergingWindowAssigner","."]
code: def _merge(
      self,
      merge_result: W,
      merge_windows: Set[W],
      state_window_result: W,
      state_windows_tobe_merged: Iterable[W],
  ):
      self._ctx.on_merge(merge_result, state_windows_tobe_merged)
  
      # clear registered timers
      for window in merge_windows:
          self._ctx.clear_trigger(window)
          self._ctx.delete_cleanup_timer(window)
  
      # merge the merged state windows into the newly resulting state window
      if state_windows_tobe_merged:
          target_acc = self._ctx.get_window_accumulators(
              state_window_result
          )
          if target_acc is None:
              target_acc = self._window_aggregator.create_accumulators()
          self._window_aggregator.set_accumulators(
              state_window_result, target_acc
          )
          for window in state_windows_tobe_merged:
              acc = self._ctx.get_window_accumulators(window)
              if acc is not None:
                  self._window_aggregator.merge(window, acc)
              # clear merged window
              self._ctx.clear_window_state(window)
          target_acc = self._window_aggregator.get_accumulators()
          self._ctx.set_window_accumulators(
              state_window_result, target_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 9 for calling the MergingWindowProcessFunction obj's underlying member method code with example usage: obj._merge(merge_result, merge_windows, state_window_result, state_windows_tobe_merged) without return types