func (l *Logger) Printf(format string, v ...interface{}) {
	l.mu.Lock()
	defer l.mu.Unlock()
	fmt.Fprintf(&l.buf, format, v...)
}
// Printf implements the log.Logger interface
Printf implements the log.Logger interface
// Printf implements the log . Logger interface
func (l *Logger) Printf(format string, v ...interface{}) {
	l.mu.Lock()
	defer l.mu.Unlock()
	fmt.Fprintf(&l.buf, format, v...)
}
func ( l * Logger ) Printf ( format string , v ... interface { } ) { l . mu . Lock ( ) defer l . mu . Unlock ( ) fmt . Fprintf ( & l . buf , format , v ... ) }
Printf implements the log.Logger interface
Printf implements the log . Logger interface