It is written `toLower`, see [https://nim-lang.org/docs/theindex.html#toLower](https://nim-lang.org/docs/theindex.html#toLower)
The type names all follow capitalization except for the really common one we found to annoying to type this way. They also predate our style guide, [https://nim-lang.org/docs/nep1.html](https://nim-lang.org/docs/nep1.html)
