As someone who has often been asked for help or advice by other programmers, I know with 100% certainty that I went to university and worked professionally with people who did this, for real.

"Hey, can you take a look at my code and help me find this bug?"
(Finding a chunk of code that has a sudden style-shift) "What is this section doing?"
"Oh that's doing XYZ."
"How does it work?"
"It calculates XYZ and (does whatever with the result)."
(Continuing to read and seeing that it actually doesn't appear to do that) "Yes, but how is it calculating XYZ?"
"I'm not 100% sure. I found it in the textbook/this 'teach yourself' book/on the PQR website."