code: public static function fromXML($xml)
      {
          $dom = new DOMDocument();
          $dom->loadXML($xml);
          $xpath = new DOMXPath($dom);
          $response = $xpath->query("//*[local-name()='GetCompetitivePricingForSKUResponse']");
          if ($response->length == 1) {
              return new MarketplaceWebServiceProducts_Model_GetCompetitivePricingForSKUResponse(($response->item(0)));
          } else {
              throw new Exception ("Unable to construct MarketplaceWebServiceProducts_Model_GetCompetitivePricingForSKUResponse from provided XML. 
                                    Make sure that GetCompetitivePricingForSKUResponse is a root element");
          }
      }
docs: Construct MarketplaceWebServiceProducts_Model_GetCompetitivePricingForSKUResponse from XML string
  
  @param $xml
  XML string to construct from
  @return MarketplaceWebServiceProducts_Model_GetCompetitivePricingForSKUResponse
  @throws Exception