syntax_data: {"ast_node_type":"variable","tokens":[{"end":45,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let mut file = fs::File::open(path)?;
context_before:     fn read_binary_file(&self, path: &Path) -> io::Result<Arc<[u8]>> {
context_after:         let len = file.metadata()?.len();