public function setProtocolVersion(string $version)
	{
		if (! is_numeric($version))
		{
			$version = substr($version, strpos($version, '/') + 1);
		}

		if (! in_array($version, $this->validProtocolVersions))
		{
			throw HTTPException::forInvalidHTTPProtocol(implode(', ', $this->validProtocolVersions));
		}

		$this->protocolVersion = $version;

		return $this;
	}