func Rparse(str, sep string) *Pair {
	return parse(str, strings.LastIndex(str, sep))
}
Rparse seperate string use last seperator string
package pair
import (
	"fmt"
	"strconv"
	"strings"
	"github.com/cosiner/gohper/strings2"
)
type Pair struct {
	Key   string
	Value string
}
func Parse(str, sep string) *Pair {
	return parse(str, strings.Index(str, sep))
}