Serious questions: what has this piece of code got to do with manual testing? I would say zero.
It is important you take anything you read with a grain of salt aka with critical mindset. If you ask the interviewer about it and they answer something like “manually testing the source code” (LOL!) then the proper answer is this process is called “code review” and is developer’s job. And if this is a source code of an automation software, then the answer is that it’s part of automated testing and again has nothing to do with manual testing 
Anyone got any other idea that I fail to see at the moment?