src/transformers/models/hubert/modeling_tf_hubert.py/TFHubertGroupNorm/_check_if_input_shape_is_none
class TFHubertGroupNorm:    def _check_if_input_shape_is_none(self, input_shape):
        dim = input_shape[self.axis]
        if dim is None:
            raise ValueError(
                "Axis " + str(self.axis) + " of "
                "input tensor should have a defined dimension "
                "but the layer received an input with shape " + str(input_shape) + "."
            )