syntax_data: {"ast_node_type":"other","tokens":[{"end":97,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// Note that we could never rely on the fact that a type such as `[_]` is trivially `!Sized`
context_before:     ///
context_after:     /// because we could be in a type environment with a bound such as `[_]: Copy`. A function with