syntax_data: {"ast_node_type":"variable","tokens":[{"end":69,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let lo = &mut self.line_cache[lo_cache_idx as usize];
context_before:                 hi.update(new_file_and_idx, span_data.hi, self.time_stamp);
context_after:                 lo.touch(self.time_stamp);