Hello. Why chunkBy!((a,b) => a[1] == b[1])( [ [1,1], [1,2], [2,2], [2,1] ]); returns a range with 3 subranges: [ [[1,1]], [[1,2], [2,2]], [[2,1]] ] I thought it would returns a range with 2 subranges [ [[1,1], [2,1]], [[1,2],[2,2]] ] It turns out that [1,1] and [2,1] are not grouped. Thanks.