code: function(fn, scope) {
          // copy items so they may be removed during iteration.
          var items = Ext.apply({}, this.map),
              key,
              length = this.length;
  
          scope = scope || this;
          for (key in items) {
              if (items.hasOwnProperty(key)) {
                  if (fn.call(scope, key, items[key], length) === false) {
                      break;
                  }
              }
          }
          return this;
      }
docs: Executes the specified function once for each item in the hash.
  Returning false from the function will cease iteration.
  
  @param {Function} fn The function to execute.
  @param {String} fn.key The key of the item.
  @param {Number} fn.value The value of the item.
  @param {Number} fn.length The total number of items in the hash.
  @param {Object} [scope] The scope to execute in. Defaults to <tt>this</tt>.
  @return {Ext.util.HashMap} this