Please answer these questions before submitting your issue. Thanks!

### What version of pprof are you using?

If you are using pprof via `go tool pprof`, what's your `go env` output?
If you run pprof from GitHub, what's the Git revision?


### What operating system and processor architecture are you using?


### What did you do?

If possible, provide a recipe for reproducing the error.
Attaching a profile you are trying to analyze is good.


### What did you expect to see?


### What did you see instead?

