class_docstr: A visitor that packs combine nodes in the graph.
  
  This visitor takes the grouped combines and performs the packing of those
  combines.
                 Before packing
             GrandParentNode
              /           \
   ExtractFromDict1     ExtractFromDict2
             /              \
         Combine1         Combine2
  
                 After packing
             GrandParentNode
                     |
               PackedCombine
                 /      \
   ExtractFromDict1'   ExtractFromDict2'
  
  The ExtractFromDict nodes after packing extracts the accumulator corresponding
  to the individual combines.
class_docstr_tok: ["A","visitor","that","packs","combine","nodes","in","the","graph",".","This","visitor","takes","the","grouped","combines","and","performs","the","packing","of","those","combines",".","Before","packing","GrandParentNode","\/","\\","ExtractFromDict1","ExtractFromDict2","\/","\\","Combine1","Combine2","After","packing","GrandParentNode","|","PackedCombine","\/","\\","ExtractFromDict1","'","ExtractFromDict2'","The","ExtractFromDict","nodes","after","packing","extracts","the","accumulator","corresponding","to","the","individual","combines","."]
code: def __init__(self, packable_combines):
      super().__init__()
      self._packable_combines = packable_combines
  
      self._combine_to_grand_parent = {}
      for grand_parent_label, group in self._packable_combines.items():
          for combine_op in group:
              self._combine_to_grand_parent[
                  combine_op.label
              ] = grand_parent_label
  
      # Cache the packed combine node.
      # Grand parent node label -> Packed combine node
      self._packed_combine_cache = {}
  
imports: import collections
  import dataclasses
  from typing import Sequence
  from tensorflow_transform import analyzer_nodes
  from tensorflow_transform import nodes
  from tensorflow_transform.beam import beam_nodes
label_desc: Use image node_id 1 to create a new _PackAccumulateCombineVisitor object from inherited base classes: _ValidationVisitor with example: obj = _PackAccumulateCombineVisitor(packable_combines)