syntax_data: {"ast_node_type":"variable","tokens":[{"end":60,"kind":"keyword","start":0,"text":"if"}]}
source_snippet:             if let Some(pat_pos) = prev_source.rfind(&pat) {
context_before:             let pat = pat.to_owned() + ws;
context_after:                 let just_after_pat_pos = pat_pos + pat.len() - 1;