src/transformers/models/big_bird/modeling_big_bird.py/BigBirdEncoder/__init__
class BigBirdEncoder:    def __init__(self, config):
        super().__init__()
        self.config = config
        self.attention_type = config.attention_type

        self.layer = nn.ModuleList(
            [BigBirdLayer(config, seed=layer_idx) for layer_idx in range(config.num_hidden_layers)]
        )