code: def associate(self, model):
          
          self._parent.set_attribute(self._foreign_key, model.get_key())
          self._parent.set_attribute(self._morph_type, model.get_morph_name())
  
          return self._parent.set_relation(
              self._relation, Result(model, self, self._parent)
          )
docs: Associate the model instance to the given parent.
  
          :type model: orator.Model
  
          :rtype: orator.Model