public function delete_rule($callback, $set_attr = true)
	{
		foreach($this->rules as $index => $rule)
		{
			if ($rule[0] === $callback)
			{
				unset($this->rules[$index]);
				break;
			}
		}

		if ($callback === 'required' and $set_attr)
		{
			unset($this->attributes[$callback]);
		}

		return $this;
	}