Function parallel_scan 

pub fn parallel_scan<T, F>(
    data: &[T],
    identity: T,
    op: F,
    mode: ScanMode,
    n_threads: usize,
) -> CoreResult<Vec<T>>
where
    T: Clone + Send + 'static,
    F: Fn(T, T) -> T + Send + Sync + 'static,

Parallel prefix scan (generalised prefix sum) using Blelloch’s algorithm.

The op must be associative (but need not be commutative).

Arguments

• data – input slice
• identity – identity element for op (needed for Exclusive scans)
• op – associative binary operator
• mode – ScanMode::Inclusive or ScanMode::Exclusive
• n_threads – degree of parallelism (0 = auto)