Function timsort 

pub fn timsort<T, E, F>(values: &mut [T], is_lt: &mut F) -> Result<(), E>
where
    T: Clone,
    F: FnMut(&T, &T) -> Result<bool, E>,

Stable adaptive mergesort (Tim Peters’ timsort with powersort’s merge-ordering policy, matching CPython 3.11+). is_lt provides comparison.