> For the complete documentation index, see [llms.txt](https://a.b.cr/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://a.b.cr/notebook/language/rust/reference.md).

# Reference

- [Capturing the Environment with Closures](https://a.b.cr/notebook/language/rust/reference/capturing-the-environment-with-closures.md): Mutable? Immutable?
- [Understanding \&mut \&mut Reference](https://a.b.cr/notebook/language/rust/reference/understanding-and-mut-and-mut-reference.md): \&mut? \&mut \&mut?? \&mut \&mut \&mut??? \&mut \&mut \&mut \&mut...