sort.go
func (s *SortFilter) flipLast() *SortFilter {
	last := s.cmp[len(s.cmp)-1]
	s.cmp[len(s.cmp)-1] = func(a, b string) int { return last(b, a) }
	return s
}
func (s *SortFilter) flipLast() *SortFilter {
	last := s.cmp[len(s.cmp)-1]
	s.cmp[len(s.cmp)-1] = func(a, b string) int { return last(b, a) }
	return s
}
func ( s * SortFilter ) flipLast ( ) * SortFilter { last := s . cmp [ len ( s . cmp ) - 1 ] s . cmp [ len ( s . cmp ) - 1 ] = func ( a , b string ) int { return last ( b , a ) } return s }
// flipLast reverses the comparison order for the last sort key.
flipLast reverses the comparison order for the last sort key .