def __split_models(self, xmlDoc):
     """generator that takes parameter xmlDoc and splits it into many
     xml files, with only one model per each"""
     elem = XML(xmlDoc)
     models = elem.find("Models")
     if models:
         elem.remove(models)
         for model in models:    
             to_return = copy.deepcopy(elem)    
             new_models = Element("Models")
             for a in models.attrib:
                 new_models.attrib[a] = models.attrib[a]
             new_models.append(model)
             to_return.append(new_models)
             yield (model.attrib['id'], to_return)
     else:
         pass #TODO return error