Function itertools::kmerge_by

pub fn kmerge_by<I, F>(
    iterable: I,
    less_than: F
) -> KMergeBy<<I::Item as IntoIterator>::IntoIter, F> 
where
    I: IntoIterator,
    I::Item: IntoIterator,
    F: FnMut(&<<I as IntoIterator>::Item as IntoIterator>::Item, &<<I as IntoIterator>::Item as IntoIterator>::Item) -> bool,

Create an iterator that merges elements of the contained iterators.

Equivalent to iterable.into_iter().kmerge_by(less_than).