func sum(arr []float64) float64 {
	total := 0.0
	for _, v := range arr {
		total += v
	}
	return total
}
// sum return total sum slice
sum return total sum slice
// sum return total sum slice
func sum(arr []float64) float64 {
	total := 0.0
	for _, v := range arr {
		total += v
	}
	return total
}
func sum ( arr [ ] float64 ) float64 { total := 0.0 for _ , v := range arr { total += v } return total }
sum return total sum slice
sum return total sum slice