syntax_data: {"ast_node_type":"variable","tokens":[{"end":24,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let expected = vec![
context_before:     let lines = sm.span_to_lines(span).unwrap();
context_after:         LineInfo { line_index: 1, start_col: CharPos(4), end_col: CharPos(6) },