syntax_data: {"ast_node_type":"variable","tokens":[{"end":42,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let bg = self.toggle_background();
context_before:     ) -> io::Result<()> {
context_after:         let valign = if mir.starts_with("(on ") && mir != "(on entry)" { "bottom" } else { "top" };