syntax_data: {"ast_node_type":"other","tokens":[{"end":68,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// `self` argument that the closure expects. For example, for a
context_before:     /// Given the `DefId` and args a closure, creates the type of
context_after:     /// `Fn` closure, this would return a reference type `&T` where