code: function (key) {
              var i = -1;
              var len;
              var subViews;
              var subMgr = new SubViewManager(null, this.parent, this.options);
              subMgr.config = this.config;
              subViews = (isArray(key)) ? key : (isFunction(key)) ? this.filter(key) : this.getByType(key);
              len = subViews.length;
              while (++i < len) {
                  subMgr.add(subViews[i]._subviewtype, subViews[i]);
              }
              return subMgr;
          }
docs: Returns a new SubViewManager instance with filtered list of subviews.
  @memberOf SubViewManager#
  @type {SubViewManager}
  @param {string|Backbone.View[]|function} key
  The key or type used to refer to a subview or subviews, or a list
  of subViews with a type found in this SubViewManager config, or a function
  that will iterate over the subviews and return true if a subview
  should be included in the filtered SubViewManager instance.
  @return {SubViewManager}