protected function getEligibleKeys(array $strings)
	{
		$eligibleKeys = [];
		foreach ($strings as $k => $string)
		{
			if (!is_array($string[0]) && isset($string[1]))
			{
				$suffix = serialize(array_slice($string, 1));
				$eligibleKeys[$suffix][] = $k;
			}
		}

		return $this->filterEligibleKeys($eligibleKeys);
	}