ensure that a new instance is returned

It's boilerplate, which when using a linter the added value is greatly reduced. Some people even insist on including it in _every single function_ which annoys me even more. To me readability is kind of important. But I guess it's mostly taste though, haha.

Also there are rare cases where a `use strict` can leak outside the module, but you've got to try real hard to make that happen haha.