def __init__(self, visitor: Visitor):
    """Init method for Traverser.

    Args:
      visitor: A `Visitor` object.
    """
    self._cached_value_nodes_values: Dict[ValueNode, Any] = {}
    self._stack: List[OperationNode] = []
    self._visitor = visitor
Init method for Traverser.

    Args:
      visitor: A `Visitor` object.
    
tensorflow_transform/nodes.py