public function delete($key)
	{
		if ($this->readOnly)
		{
			throw new \RuntimeException('Changing values on this Data Container is not allowed.');
		}

		$this->isModified = true;

		if (($result = Arr::delete($this->data, $key)) === false and $this->parentEnabled)
		{
			$result = $this->parent->delete($key);
		}

		return $result;
	}