src/transformers/models/mobilebert/modeling_mobilebert.py/BottleneckLayer/__init__
class BottleneckLayer:    def __init__(self, config):
        super().__init__()
        self.dense = nn.Linear(config.hidden_size, config.intra_bottleneck_size)
        self.LayerNorm = NORM2FN[config.normalization_type](config.intra_bottleneck_size, eps=config.layer_norm_eps)