Function rrf_multi 

pub fn rrf_multi<I, L>(lists: &[L], config: RrfConfig) -> Vec<(I, f32)>
where
    I: Clone + Eq + Hash,
    L: AsRef<[(I, f32)]>,

RRF for 3+ result lists.

Empty Lists

If lists is empty, returns an empty result. If some lists are empty, they contribute zero scores (documents not appearing in those lists receive no contribution from them).

Complexity

O(L×N + U×log U) where L = number of lists, N = average list size, U = number of unique document IDs across all lists.