pub trait ReceiveInFile<IdN, Idx, IdO, O>: Sized + ReceiveParent<IdN, Self::S1> + SetLen<IdO, Self::O0> {
type S1: ReceiveIdx<Idx, Self::S2>;
type S2: ReceiveOffset<IdO, Self::S3>;
type S3: ReceiveIdxNoSpace<Idx, Self>;
type O0: SetNode<IdN, O>;
}