Function differential_dataflow::algorithms::prefix_sum::aggregate

pub fn aggregate<G, K, D, F>(
    collection: Collection<G, ((usize, K), D)>, 
    combine: F
) -> Collection<G, ((usize, usize, K), D)> where
    G: Scope,
    G::Timestamp: Lattice,
    K: ExchangeData + Hash,
    D: ExchangeData + Hash,
    F: Fn(&K, &D, &D) -> D + 'static, 

Accumulate data in collection into all powers-of-two intervals containing them.