syntax_data: {"ast_node_type":"other","tokens":[{"end":79,"kind":"keyword","start":0,"text":"///"}]}
source_snippet: ///    and the up-var has the type `Foo`, then that field of U will be `&Foo`).
context_before: ///   (borrowed, if appropriate; that is, if a U field represents a by-ref upvar,
context_after: ///