I initially discovered Pure Storage at a career fair. At the fair, they handed out a simple multithreaded program (in several languages; I chose Java) for participants to find bugs in.

I passed that stage and interviewed with a member of the team at a second career fair.

Whiteboard coding session. The interviewer wrote a simple program on the board that I had to debug.

He was primarily looking for how I went about debugging the program.

The program had several function calls, which the interviewer described the output of verbally.

The functions themselves were obscure and certainly had side effects, so they were not simple to debug.