Frustrating experience. I had heard good things about Walmart Tech, so I stopped by their booth at a career fair, and I was asked to interview later that day. Details of what position the interview was specifically for were not made clear, but I figured I could learn more in the interview. When I arrived for the interview, I waited for a half hour past my scheduled time before they realized that the recruiter I was supposed to interview with had accidentally overbooked. So they sent me into a room with a random guy. He didn't know what he was specifically interviewing me for, didn't even ask for my resume, and went a half hour over my allotted time asking different coding questions. Some questions weren't clear, and I did not know what he was trying to ask at times. Needless to say, I came out very frustrated with the process, especially since I had rearranged my schedule for this.

Explain the concept of async operations.