See [https://github.com/nim-lang/Nim/blob/devel/doc/contributing.rst#evolving-the-stdlib](https://github.com/nim-lang/Nim/blob/devel/doc/contributing.rst#evolving-the-stdlib) for a rationale what goes into the stdlib. But `isFloat` will have a hard time, because I don't see the point. It only would encourage code like `if isFloat(x): parseFloat(x)`.
`unwrap_or`: Well, Nim is not Rust. Plus `options.get` already exists.
