code: def get_tensor_dependencies(tensor):
      
      dependencies = set()
      dependencies.update(tensor.op.inputs)
      for sub_op in tensor.op.inputs:
          dependencies.update(get_tensor_dependencies(sub_op))
      return dependencies
docs: Utility method to get all dependencies (including placeholders) of a tensor (backwards through the graph).
  
      Args:
          tensor (tf.Tensor): The input tensor.
  
      Returns: Set of all dependencies (including needed placeholders) for the input tensor.