syntax_data: {"ast_node_type":"other","tokens":[{"end":49,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:         // Ensure we're at the same expansion ID.
context_before:     fn merge_spans(&self, sp_lhs: Span, sp_rhs: Span) -> Option<Span> {
context_after:         if !sp_lhs.eq_ctxt(sp_rhs) {