syntax_data: {"ast_node_type":"other","tokens":[{"end":63,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     ///    * the LHS span must start at or before the RHS span.
context_before:     ///    * the LHS span needs to end on the same line the RHS span begins,
context_after:     fn merge_spans(&self, sp_lhs: Span, sp_rhs: Span) -> Option<Span> {