I suggest overriding the default value of `vbm` here instead of declaring two alternate versions of the flag (combined with the flag declaration comment above).
Although I don't see it here, I'm assuming that `flag.Parse()` is getting called **after** this `config()` function (which would normally be placed into an `init()`... I'm not sure why this one is not.

Like this:
```go
*vbm = filepath.Join(p, "VBoxManage.exe")
```

Then, delete the next two lines.