sort.go
func (s *SortFilter) NumDecreasing(n int) *SortFilter {
	return s.Num(n).flipLast()
}
func (s *SortFilter) NumDecreasing(n int) *SortFilter {
	return s.Num(n).flipLast()
}
// NumDecreasing sets the next sort key to sort by column n in reverse
// numeric order. Column 0 means the entire string. Items that do not
// have column n sort to the end.  Items whose column n is not a
// number sort to the front.