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 visit(self, operation_def, input_values):
      self.validate_operation_def(operation_def)
      # If we see a combine node which can be packed, create the packed combine
      # node and cache it as we will use the same packed node for all the combines
      # in the group.
      if operation_def.label in self._combine_to_grand_parent:
          return self._get_packed_combine(operation_def, input_values)
      return nodes.OperationNode(operation_def, input_values).outputs
  
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 2 for calling the _PackAccumulateCombineVisitor obj's underlying member method code with example usage: obj.visit(operation_def, input_values) and returns: nodes, self