syntax_data: {"ast_node_type":"variable","tokens":[{"end":48,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let hi_line = hi.line.saturating_sub(1);
context_before:         // asserting that the line numbers here are all indeed 1-based.
context_after:         for line_index in lo.line.saturating_sub(1)..hi_line {