Function diff 

pub fn diff<Old, New, D>(
    alg: Algorithm,
    d: &mut D,
    old: &Old,
    old_range: Range<usize>,
    new: &New,
    new_range: Range<usize>,
) -> Result<(), D::Error>
where
    Old: Index<usize> + ?Sized,
    New: Index<usize> + ?Sized,
    D: DiffHook,
    Old::Output: Hash + Eq + Ord,
    New::Output: PartialEq<Old::Output> + Hash + Eq + Ord,

Creates a diff between old and new with the given algorithm.

Diffs old, between indices old_range and new between indices new_range.