def METHOD_NAME(self, var_list):
    super().METHOD_NAME(var_list)
    if hasattr(self, "_built") and self._built:
        return
    self._built = True
    self._accumulators = []
    initializer = initializers.Constant(self.initial_accumulator_value)
    for var in var_list:
        self._accumulators.append(
            self.add_variable_from_reference(
                var,
                "accumulator",
                initial_value=initializer(shape=var.shape, dtype=var.dtype),
            )
        )