如何将Std Class对象从SoapClient命令返回到XML

The response of a SoapClient command returned it:

stdClass Object
(
    [ExecutarXMLResult] => stdClass Object
    (
        [any] => <i9proerp xmlns=""><listatomador id_pessoa="5251" nm_pessoa="nome1" nr_cnpj_cpf="1"/><listatomador id_pessoa="939" nm_pessoa="nome2" nr_cnpj_cpf="2"/><listatomador id_pessoa="3285" nm_pessoa="nome3" nr_cnpj_cpf="3"/></i9proerp>
     )
 )

How I get the return into a XML?

Assume

$obj = ... // result from soap, as stated above
$obj->ExecutarXMLResult->any (XML string)

Whether is a valid XML string, that's not part of this discussion.