docs: function sort(itemsKey, sortDefinition) {
        Ember.assert('Ember.computed.sort requires two arguments: an array key to sort and ' +
          'either a sort properties key or sort function', arguments.length === 2);
  
        if (typeof sortDefinition === 'function') {
          return customSort(itemsKey, sortDefinition);
        } else {
          return propertySort(itemsKey, sortDefinition);
        }
      }