syntax_data: {"ast_node_type":"other","tokens":[{"end":47,"kind":"keyword","start":0,"text":"assert!(span_data.lo"}]}
source_snippet:         assert!(span_data.lo >= lo.line.start);
context_before:         // end in newline, hence the inclusive upper bounds below.
context_after:         assert!(span_data.lo <= lo.line.end);