First draft of a 'Try -> map' puzzler

Another option here would be:
```
println(divideThenSqrt(18, 2)).get
println(divideThenSqrt(18, -2)).get
```
That removes the wrapping "Success(...)" and "Failure(...)" from the responses, but I wonder whether what `.get` does is sufficiently clear to readers? This is not meant to be a `.get` quiz, after all...