syntax_data: {"ast_node_type":"variable","tokens":[{"end":73,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:             let new_file_and_idx = self.file_for_position(span_data.lo)?;
context_before:         let new_file_and_idx = if !file_contains(&self.line_cache[oldest].file, span_data.lo) {
context_after:             if !file_contains(&new_file_and_idx.0, span_data.hi) {