writer.go
func (f *FileLogger) p(str string) {
	f.mu.RLock()
	defer f.mu.RUnlock()

	f.lg.Output(2, str)
	f.pc(str)
}
func (f *FileLogger) p(str string) {
	f.mu.RLock()
	defer f.mu.RUnlock()

	f.lg.Output(2, str)
	f.pc(str)
}
func ( f * FileLogger ) p ( str string ) { f . mu . RLock ( ) defer f . mu . RUnlock ( ) f . lg . Output ( 2 , str ) f . pc ( str ) }
// print log
print log