syntax_data: {"ast_node_type":"other","tokens":[{"end":13,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     ///     }
context_before:     ///         pub fn $f() {} // `$f`'s `SyntaxContext` is empty.
context_after:     ///     foo::f(); // `f`'s `SyntaxContext` has a single `ExpnId` from `m`