func (g *Glg) Errorf(format string, val ...interface{}) error {
	return g.out(ERR, format, val...)
}
func (g *Glg) Errorf(format string, val ...interface{}) error {
	return g.out(ERR, format, val...)
}
func ( g * Glg ) Errorf ( format string , val ... interface { } ) error { return g . out ( ERR , format , val ... ) }
// Errorf outputs formatted Error log
Errorf outputs formatted Error log