Incorrect code snippets / feature description (?)

[gl4eqen]

Hey,
code snippet within scope/borrow/alias.md is completely valid & compiles after uncommenting line 22 //let mutable_borrow = &mut point.

I'd love to fix it but currently I'm still struggling to get a grasp on a language. As far as I understand it is acceptable to have both many immutable and mutable references within the same scope but not to.. use them in a interleaved manner?