code: function(o) {
          var me = this,
              key;
  
          if (o != null) {
              // If
              //     We have not been forced into using linear lookup by a usage of the 2 arg form of add
              // and
              //     The key extraction function yields a key
              // Then use the map to determine object presence.
              if (!me.useLinearSearch && (key = me.getKey(o))) {
                  return this.map[key] != null;
              }
  
              // Fallback: Use linear search
              return Ext.Array.indexOf(this.items, o) !== -1;
          }
          
          return false;
      }
docs: Returns true if the collection contains the passed Object as an item.
  @param {Object} o  The Object to look for in the collection.
  @return {Boolean} True if the collection contains the Object as an item.
  @since Ext 1