Document that `index` and `index_mut` can panic
Document that `index` and `index_mut` can panic
graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,aidancully/rust