src/transformers/models/bit/modeling_bit.py/BitModel/__init__
class BitModel:    def __init__(self, config):
        super().__init__(config)
        self.config = config

        self.embedder = BitEmbeddings(config)

        self.encoder = BitEncoder(config)
        self.norm = (
            BitGroupNormActivation(config, num_channels=config.hidden_sizes[-1])
            if config.layer_type == "preactivation"
            else nn.Identity()
        )

        self.pooler = nn.AdaptiveAvgPool2d((1, 1))
        # Initialize weights and apply final processing
        self.post_init()