How to iterate through slice in chunk

iterate-slice-in-chunk.go

// int64 version, iterate through slice in chunk, breaks on first error.
func IterateSliceInChunk(slice []int64, chunkSize int, work func([]int64) error) error {
	if chunkSize < 1 {
		panic("chunk size is below one")
	}
	var offset = 0
	var err error
	for err == nil {
		lower, upper := offset, offset+chunkSize
		if upper >= len(slice) {
			err = work(slice[lower:])
			break
		} else {
			err = work(slice[lower:upper])
			offset = upper
		}
	}
	return err
}