I'd say `expect` is idiomatic for situations in which the error is due to an unrecoverable logic flaw. If it's due to user error, I'd want to do something else

I'd say `expect` is idiomatic for situations in which the error is due to an unrecoverable logic flaw. If it's due to user error, I'd want to do something else just to customize the error message format. Also, as another commenter mentioned, the `let process = p.unwrap()` is suspicious. I imagine this can happen if a process simply exits between being returned from the `/proc` traversal and `opendir("/proc/<pid>")`. If the error is `ENOENT`, it should simply continue to the next pid without printing an error at all.