func NewMulti(vals ...interface{}) LogBackend {
	if len(vals)%2 != 0 {
		Fail(e.New("parameters must be in pair of LogBackend and Formatter"))
		return nil
	}
	l := len(vals) / 2
	mp := make([]LogBackend, 0, l)
	for i := 0; i < len(vals); i += 2 {
		bak, ok := vals[i].(LogBackend)
		if !ok {
			Fail(e.New("not a LogBackend"))
			return nil
		}
		f, ok := vals[i+1].(Formatter)
		if !ok {
			Fail(e.New("not a Formatter"))
			return nil
		}
		bak.F(f)
		mp = append(mp, bak)
	}
	return &MultiLog{
		mp: mp,
	}
}
func NewMulti(vals ...interface{}) LogBackend {
	if len(vals)%2 != 0 {
		Fail(e.New("parameters must be in pair of LogBackend and Formatter"))
		return nil
	}
	l := len(vals) / 2
	mp := make([]LogBackend, 0, l)
	for i := 0; i < len(vals); i += 2 {
		bak, ok := vals[i].(LogBackend)
		if !ok {
			Fail(e.New("not a LogBackend"))
			return nil
		}
		f, ok := vals[i+1].(Formatter)
		if !ok {
			Fail(e.New("not a Formatter"))
			return nil
		}
		bak.F(f)
		mp = append(mp, bak)
	}
	return &MultiLog{
		mp: mp,
	}
}
//NewMulti creates a MultiLog