func callsite(flag uint32) (string, int) {
	_, file, line, ok := runtime.Caller(calldepth)
	if !ok {
		return "???", 0
	}
	if flag&Lshortfile != 0 {
		short := file
		for i := len(file) - 1; i > 0; i-- {
			if os.IsPathSeparator(file[i]) {
				short = file[i+1:]
				break
			}
		}
		file = short
	}
	return file, line
}
func callsite(flag uint32) (string, int) {
	_, file, line, ok := runtime.Caller(calldepth)
	if !ok {
		return "???", 0
	}
	if flag&Lshortfile != 0 {
		short := file
		for i := len(file) - 1; i > 0; i-- {
			if os.IsPathSeparator(file[i]) {
				short = file[i+1:]
				break
			}
		}
		file = short
	}
	return file, line
}
func callsite ( flag uint32 ) ( string , int ) { _ , file , line , ok := runtime . Caller ( calldepth ) if ! ok { return " " , 0 } if flag & Lshortfile != 0 { short := file for i := len ( file ) - 1 ; i > 0 ; i -- { if os . IsPathSeparator ( file [ i ] ) { short = file [ i + 1 : ] break } } file = short } return file , line }
// callsite returns the file name and line number of the callsite to the
// subsystem logger.
callsite returns the file name and line number of the callsite to the subsystem logger .