code: def xpathVariableLookupNS(self, name, ns_uri):
          
          ret = libxml2mod.xmlXPathVariableLookupNS(self._o, name, ns_uri)
          if ret is None:raise xpathError('xmlXPathVariableLookupNS() failed')
          return xpathObjectRet(ret)
docs: Search in the Variable array of the context for the given
             variable value.