Example
The zero value of slice is nil, which has the length and capacity 0. A nil slice has no underlying array. But there are also non-nil slices of length and capacity 0, like []int{} or make([]int, 5)[5:].
Any type that have nil values can be converted to nil slice:
s = []int(nil)
To test whether a slice is empty, use:
if len(s) == 0 {
fmt.Ptintf("s is empty.")
}
