code: func OverlappingBinsFor(beg, end int) []uint32 {
  	end--
  	list := []uint32{level0}
  	for _, r := range []struct {
  		offset, shift uint32
  	}{
  		{level1, level1Shift},
  		{level2, level2Shift},
  		{level3, level3Shift},
  		{level4, level4Shift},
  		{level5, level5Shift},
  	} {
  		for k := r.offset + uint32(beg>>r.shift); k <= r.offset+uint32(end>>r.shift); k++ {
  			list = append(list, k)
  		}
  	}
  	return list
  }
docs: // OverlappingBinsFor returns the bin numbers for all bins overlapping
  // an interval covering [beg,end) (zero-based, half-close-half-open).