{"ast_node_type":"variable","tokens":[{"end":86,"kind":"keyword","start":0,"text":"let"}]}
                    let line_begin_pos = (line_begin_in_file - start_bpos).to_usize();
                    let line_begin_in_file = source_file.line_begin_pos(pos_in_file);
                    let col = CharPos(text[line_begin_pos..pos].chars().count());