syntax_data: {"ast_node_type":"variable","tokens":[{"end":44,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:             let num_diffs = lines.len() - 1;
context_before:             let diff_iter = lines.array_windows().map(|&[fst, snd]| snd - fst);
context_after:             let mut raw_diffs;