Function differential_dataflow::algorithms::graphs::propagate::propagate_at

pub fn propagate_at<G, N, L, F>(
    edges: &Collection<G, (N, N)>, 
    nodes: &Collection<G, (N, L)>, 
    logic: F
) -> Collection<G, (N, L)> where
    G: Scope,
    G::Timestamp: Lattice + Ord,
    N: ExchangeData + Hash,
    L: ExchangeData,
    F: Fn(&L) -> u64 + 'static, 

Propagates labels forward, retaining the minimum label.