syntax_data: {"ast_node_type":"other","tokens":[{"end":69,"kind":"keyword","start":0,"text":"///"}]}
source_snippet: /// - CS represents the *closure signature*, representing as a `fn()`
context_before: ///   `Ty::to_opt_closure_kind` for details.
context_after: ///   type. For example, `fn(u32, u32) -> u32` would mean that the closure