syntax_data: {"ast_node_type":"other","tokens":[{"end":64,"kind":"keyword","start":0,"text":"write!(f,"}]}
source_snippet:                 write!(f, "({op:?}: ({:?}: {:?}))", rhs, rhs_ty)
context_before:                 let (rhs_ty, rhs) = self.unop_args();
context_after:             }