src/transformers/models/convbert/modeling_convbert.py/GroupedLinearLayer/__init__
class GroupedLinearLayer:    def __init__(self, input_size, output_size, num_groups):
        super().__init__()
        self.input_size = input_size
        self.output_size = output_size
        self.num_groups = num_groups
        self.group_in_dim = self.input_size // self.num_groups
        self.group_out_dim = self.output_size // self.num_groups
        self.weight = nn.Parameter(torch.empty(self.num_groups, self.group_in_dim, self.group_out_dim))
        self.bias = nn.Parameter(torch.empty(output_size))