syntax_data: {"ast_node_type":"variable","tokens":[{"end":86,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let new_file_and_idx = if !file_contains(&self.line_cache[oldest].file, pos) {
context_before:         // If the entry doesn't point to the correct file, get the new file and index.
context_after:             Some(self.file_for_position(pos)?)