Function rolling_extreme 

pub fn rolling_extreme<T, F>(
    data: &[T],
    mask: Option<&Bitmask>,
    subwindow: usize,
    better: F,
    zero: T,
) -> (Vec64<T>, Bitmask)
where
    T: Copy,
    F: FnMut(&T, &T) -> bool,

Allocating variant: creates new output buffers internally.