syntax_data: {"ast_node_type":"variable","tokens":[{"end":41,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let offset = bpos - sf.start_pos;
context_before:         let sf = Arc::clone(&(*self.files.borrow().source_files)[idx]);
context_after:         SourceFileAndBytePos { sf, pos: offset }