code: function _startHideAnimation(item, prevItem, size) {
          var spec = item.options.hide.animation ? item.options.hide.animation.call(undefined, false, size) : {};
          item.endSpec = spec;
          item.startSpec = {
              opacity: 1,
              transform: Transform.identity
          };
          if (!item.halted) {
              item.mod.halt();
              var callback = item.hideCallback;
              if (spec.transform) {
                  item.mod.setTransform(spec.transform, item.options.hide.transition, callback);
                  callback = undefined;
              }
              if (spec.opacity !== undefined) {
                  item.mod.setOpacity(spec.opacity, item.options.hide.transition, callback);
                  callback = undefined;
              }
              if (callback) {
                  callback();
              }
          }
      }
docs: Starts the hide animation.