He was my manager/mentor when I interned at Cisco. Very smart and humble guy and was always helpful. I tried though to stay mostly self directed and self reliant when solving the problem or task the group had given me. I eventually got stuck trying to figure out how to reassemble IP fragments into a whole packet. I probably spent a week or so, laying my concerns in group meetings, and trying to find the right data structure to do it.

Then one day, he gives me freestanding C code that was superbly written, with some macros for benchmarking, etc. For the most part it worked but needed some massaging for edge cases and such, but it was so beautiful and solved my immediate needs. I was unblocked but the whole ordeal has since been imprinted in my mind. He didn't give any context when handing the code, but I later figured out he implemented the algorithm as described in RFC 815. Deep in the annals of history and literature in networking that isn't really covered by any contemporary networking text books or sources.

Anyways now that I'm a mentor/tech lead these days, I'm always looking for my opportunity to help unblock someone by writing some very specific hard to implement code.