Return (namespaceURI, name) for a type attribue of the given
           element, or None if the element does not have a type attribute.

def getTypeRef(self, element):
        """Return (namespaceURI, name) for a type attribue of the given
           element, or None if the element does not have a type attribute."""
        typeattr = self.getAttr(element, 'type', default=None)
        if typeattr is None:
            return None
        parts = typeattr.split(':', 1)
        if len(parts) == 2:
            nsuri = self.findNamespaceURI(parts[0], element)
        else:
            nsuri = self.findDefaultNS(element)
        return (nsuri, parts[1])