syntax_data: {"ast_node_type":"other","tokens":[{"end":54,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// `expn_id.is_descendant_of(ctxt.outer_expn())`.
context_before:     /// `expn_id.outer_expn_is_descendant_of(ctxt)` is equivalent to but faster than
context_after:     #[inline]