code: func (l *Logger) Logf(level LogLevel, format string, v ...interface{}) {
  	if l.getLevel() <= level {
  		l.getHandler().Log(l.name, level, fmt.Sprintf(format, v...), 1)
  	}
  }
docs: // Logf logs a format string with values if the logger's level is the provided
  // level or even more permissive.