func (e *edit) ReplaceN(r []Replacer, n int) error {
	return e.genReplace(r, n)
}
func (e *edit) ReplaceN(r []Replacer, n int) error {
	return e.genReplace(r, n)
}
// ReplaceN replaces regular expressions mathed in r. The count determines the
// number to match:
//   n > 0: at most n matches
//   n == 0: the result is none
//   n < 0: all matches