base.go
func (b *Base) Errorf(msg string, a ...interface{}) error {
	return b.Log(LevelError, nil, msg, a...)
}
func (b *Base) Errorf(msg string, a ...interface{}) error {
	return b.Log(LevelError, nil, msg, a...)
}
/*
Errorf uses msg as a format string with subsequent parameters as values and logs
the resulting message to all added loggers at LogLevel.LevelError
*/