{"ast_node_type":"other","tokens":[{"end":71,"kind":"keyword","start":0,"text":"Ok(Err(err))"}]}
            Ok(Err(err)) => Err(ProcMacroExpansionError::Panic(err.0)),
            Ok(Ok(subtree)) => Ok(subtree),
            Err(err) => Err(ProcMacroExpansionError::System(err.to_string())),