src/transformers/models/reformer/modeling_reformer.py/ChunkReformerFeedForward/__init__
class ChunkReformerFeedForward:    def __init__(self, config):
        super().__init__()
        self.chunk_size_feed_forward = config.chunk_size_feed_forward
        self.seq_len_dim = 1

        self.layer_norm = nn.LayerNorm(config.hidden_size, eps=config.layer_norm_eps)
        self.dense = ReformerFeedForwardDense(config)
        self.output = ReformerFeedForwardOutput(config)