code: def describe_path_as_analyzer_cache_hash(
      x: Optional[Union[tf.Operation, tf.Tensor, str]],
      parents: Optional[List[bytes]] = None,
  ) -> Optional[bytes]:
      """Constructs a hash to describe a unique TF graph path.
  
      Note: We do not rely on names for hashing since it can be fragile.
  
      Args:
        x: The current TF graph node.
        parents: Results of previous calls to this function, where x was an ancestor
          to the current node x.
  
      Returns:
        A bytes hash of the path from x to its sources. None if x is None.
      """
      # This may happen in cases where tensors are outputs of previous analyzers,
      # we don't need to describe a path for those.
      if x is None:
          assert parents is None
          return None
      parents = parents or []
      if any(p is None for p in parents):
          return None
  
      if isinstance(x, tf.Operation):
          values = _serialize_op_attr(x.node_def.attr)
      elif isinstance(x, tf.Tensor):
          # No need to add x.op to the hash since that should be included in parents.
          values = [tf.compat.as_str_any(x.value_index)]
      else:
          assert isinstance(x, (str, bytes))
          values = [x]
  
      h = hashlib.sha1()
      for value in values:
          encoded = tf.compat.as_bytes(value)
          h.update(encoded)
  
      for p in parents:
          h.update(p)
  
      return h.digest()
  
imports: import collections
  import copy
  import hashlib
  import itertools
  from typing import Iterable, List, Mapping, Optional, Set, Union
  import uuid
  from absl import logging
  import tensorflow
  from tensorflow_transform import analyzer_nodes
  from tensorflow_transform import common_types
  from tensorflow_transform import nodes
  from tensorflow_transform import tf_utils
  from tfx_bsl.types import tfx_namedtuple
  from tensorflow.python.framework import composite_tensor
  from tensorflow.python.framework import func_graph
  from tensorflow.python.framework import function_def_to_graph
  from tensorflow.python.util import object_identity
label_desc: Use image node_id 8 for calling a global function with example usage: describe_path_as_analyzer_cache_hash(x, parents) and returns: h, None, None