message: Remove stale todo.
  Explicit support is not required for SparseTensors, since they are composites
  and this code supports CompositeTensors.
diff: @@ -3924,8 +3924,6 @@ tensorflow::Status TFE_Py_EncodeArgHelper(PyObject* arg,
  // `include_tensor_ranks_only` allows caching on arguments excluding shape info,
  // so that a slow path using relaxed shape can rely on a cache key that excludes
  // shapes.
  -//
  -// TODO(nareshmodi): Add support for sparse tensors.
  PyObject* TFE_Py_EncodeArg(PyObject* arg, bool include_tensor_ranks_only) {
  EncodeResult result;
  const auto status =
  