starts with conv layer - `ch_in` channels in - then has `num_blocks` `ResLayer`

def make_group_layer(self, ch_in:int, num_blocks:int, stride:int=1):
        "starts with conv layer - `ch_in` channels in - then has `num_blocks` `ResLayer`"
        return [conv_bn_lrelu(ch_in, ch_in*2,stride=stride)
               ] + [(ResLayer(ch_in*2)) for i in range(num_blocks)]