syntax_data: {"ast_node_type":"variable","tokens":[{"end":71,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let sf = Arc::clone(&(*self.files.borrow().source_files)[idx]);
context_before:         let idx = self.lookup_source_file_idx(bpos);
context_after:         let offset = bpos - sf.start_pos;