{"ast_node_type":"variable","tokens":[{"end":70,"kind":"keyword","start":0,"text":"let"}]}
        let cache_key = (source_file.stable_id, source_file.src_hash);
    pub(crate) fn add_source_file(&mut self, source_file: &SourceFile) -> FileId {
        *self.created_files.entry(cache_key).or_insert_with(|| {