src/transformers/models/convbert/modeling_tf_convbert.py/GroupedLinearLayer/build
class GroupedLinearLayer:    def build(self, input_shape):
        self.kernel = self.add_weight(
            "kernel",
            shape=[self.group_out_dim, self.group_in_dim, self.num_groups],
            initializer=self.kernel_initializer,
            trainable=True,
        )

        self.bias = self.add_weight(
            "bias", shape=[self.output_size], initializer=self.kernel_initializer, dtype=self.dtype, trainable=True
        )