slices.go
func (s StringSlice) IndexOf(str string) int {
	for i, v := range s {
		if str == v {
			return i
		}
	}

	return -1
}
func (s StringSlice) IndexOf(str string) int {
	for i, v := range s {
		if str == v {
			return i
		}
	}

	return -1
}
func ( s StringSlice ) IndexOf ( str string ) int { for i , v := range s { if str == v { return i } } return - 1 }
// IndexOf looks for specified string into current slice.
IndexOf looks for specified string into current slice .