{"ast_node_type":"other","tokens":[{"end":81,"kind":"keyword","start":0,"text":"err.span_note(self.expr_span,"}]}
                    err.span_note(self.expr_span, "this reference is immutable");
                    err.span_label(self.span, "invalid cast");
                    err.span_note(self.cast_span, "trying to cast to a mutable reference type");