+/// @todo backwards compat: return string instead of callable
+/**
+ * @see PhpXmlRpc\Wrapper::wrapXmlrpcMethod
+ * @param xmlrpc_client $client
+ * @param string $methodName
+ * @param int|array $extraOptions the usage of an int as signature number is deprecated, use an option in $extraOptions
+ * @param int $timeout deprecated, use an option in $extraOptions
+ * @param string $protocol deprecated, use an option in $extraOptions
+ * @param string $newFuncName deprecated, use an option in $extraOptions
+ * @return array|callable|false
+ */