syntax_data: {"ast_node_type":"variable","tokens":[{"end":86,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let raw_diffs = d.read_raw_bytes(bytes_per_diff * num_diffs).to_vec();
context_before:                 let num_diffs = num_lines as usize - 1;
context_after:                 SourceFileLines::Diffs(SourceFileDiffs { bytes_per_diff, num_diffs, raw_diffs })