class_docstr: A placeholder that will ultimately be translated to a PTransform.
  
  Attributes:
    operation_def: An `OperationDef`.
    inputs: A tuple of `ValueNode`s.
code: def operation_def(self):
      return self._operation_def
  
imports: import abc
  import collections
  import dataclasses
  from typing import Any, Collection, Dict, List, Optional, Tuple
  import pydot
label_desc: Use image node_id 3 for calling the OperationNode obj's underlying member method code with example usage: obj.operation_def() and returns: self