protected function prepareRules(array $rules, array $attributes)
	{
		// start and deadline are both optional, but if they're both set, we
		// want to validate that the deadline is after the start.
		if (!empty($attributes['start']) && !empty($attributes['deadline'])) {
			// because we're validating that start and deadline are valid date/
			// time strings, we can use the "after" validation rule.
			$rules['deadline'][] = 'after:' . $attributes['start'];
		}

		// always return the modified rules!
		return $rules;
	}