docs: def parse(self, ps, **kw):
          '''
          ps -- ParsedSoap instance
          '''
          namespaceURI = self.wsAddressURI
          elements = ("MessageID","Action","To","From","RelatesTo")
          d = {namespaceURI:elements}
          typecodes = self._getWSAddressTypeCodes(**d)
          pyobjs = ps.ParseHeaderElements(typecodes)
          self._messageID = pyobjs[(namespaceURI,elements[0])]
          self._action = pyobjs[(namespaceURI,elements[1])]
          self._addressTo = pyobjs[(namespaceURI,elements[2])]
          self._from = pyobjs[(namespaceURI,elements[3])]
          self._relatesTo = pyobjs[(namespaceURI,elements[4])]