src/transformers/models/reformer/modeling_reformer.py/ReformerLayer/__init__
class ReformerLayer:    def __init__(self, config, layer_id=0):
        super().__init__()
        self.attention = ReformerAttention(config, layer_id)
        # dropout requires to have the same
        # seed for forward and backward pass
        self.attention_seed = None
        self.feed_forward_seed = None

        self.feed_forward = ChunkReformerFeedForward(config)