src/transformers/models/funnel/modeling_funnel.py/FunnelAttentionStructure/__init__
class FunnelAttentionStructure:    def __init__(self, config: FunnelConfig) -> None:
        super().__init__()
        self.config = config
        self.sin_dropout = nn.Dropout(config.hidden_dropout)
        self.cos_dropout = nn.Dropout(config.hidden_dropout)
        # Track where we are at in terms of pooling from the original input, e.g., by how much the sequence length was
        # divided.
        self.pooling_mult = None