internalState[] = $value; } else { $this->internalState[$offset] = $value; } } /** * Checks whether an internal key exists. * * @param string $offset * * @return bool */ public function offsetExists($offset) { return isset($this->internalState[$offset]); } /** * Unsets an internal key. * * @param string $offset */ public function offsetUnset($offset) { unset($this->internalState[$offset]); } /** * Retrieves an internal key. * * @param string $offset * * @return mixed|null */ public function offsetGet($offset) { return $this->offsetExists($offset) ? $this->internalState[$offset] : null; } }