149         foreach ($this->_group->pop() as $index => $exception) {
150             $this[$index] = $exception;
171      * @param   mixed  $index    Index.
174     public function offsetExists($index)  argument
177             if (isset($group[$index])) {
188      * @param   mixed  $index    Index.
191     public function offsetGet($index)  argument
194             if (isset($group[$index])) {
195                 return $group[$index];
205      * @param   mixed       $index        Index.
209     public function offsetSet($index, $exception)  argument
217         if (null === $index ||
218             true === is_int($index)) {
221             $group[$index] = $exception;
230      * @param   mixed  $index    Index.
233     public function offsetUnset($index)  argument
236             if (isset($group[$index])) {
237                 unset($group[$index]);