def set_incremental_state(
    module: "MultiheadAttention",
    incremental_state: Optional[Dict[str, Dict[str, Optional[Tensor]]]],
    key: str,
    value: Dict[str, Optional[Tensor]],
) -> Optional[Dict[str, Dict[str, Optional[Tensor]]]]:
    """Helper for setting incremental state for an nn.Module."""
    if incremental_state is not None:
        result = module.set_incremental_state(incremental_state, key, value)
        if result is not None:
            incremental_state = result
    return incremental_state
Helper for setting incremental state for an nn.Module.
fairseq/utils.py