string.go
func (s StringGroupedNumberPostfixSorter) Swap(i, j int) {
	s[i], s[j] = s[j], s[i]
}
func (s StringGroupedNumberPostfixSorter) Swap(i, j int) {
	s[i], s[j] = s[j], s[i]
}
func ( s StringGroupedNumberPostfixSorter ) Swap ( i , j int ) { s [ i ] , s [ j ] = s [ j ] , s [ i ] }
// Swap swaps the elements with indexes i and j.
Swap swaps the elements with indexes i and j .