docs: def getAttributeQName(self, attribute):
          """return requested attribute value as (namespace,name) or None 
          """
          qname = self.getAttribute(attribute)
          if isinstance(qname, TypeDescriptionComponent) is True:
              return qname
          if qname is None:
              return None
  
          prefix,ncname = SplitQName(qname)
          namespace = self.getXMLNS(prefix)
          return TypeDescriptionComponent((namespace,ncname))