code: def save(self, model, joining=None, touch=True):
          
          if joining is None:
              joining = {}
  
          model.save({'touch': False})
  
          self.attach(model.get_key(), joining, touch)
  
          return model
docs: Save a new model and attach it to the parent model.
  
          :type model: eloquent.Model
          :type joining: dict
          :type touch: bool
  
          :rtype: eloquent.Model