message: Remove the usage of tf private API ops._as_graph_element.
diff: @@ -3971,7 +3971,7 @@ class GraphExecutionFunction:
  connection = callable_opts.tensor_connection.add()
  if x.dtype != y.dtype:
  y = math_ops.cast(y, dtype=x.dtype)
  - from_tensor = ops._as_graph_element(y)
  + from_tensor = _as_graph_element(y)
  if from_tensor is None:
  from_tensor = y
  connection.from_tensor = from_tensor.name # Data tensor
  