public static function tenantHost(string $tenant_part) : string {
		// generate link to system tenant
		$domain_level = (int) \Application::get('application.structure.tenant_domain_level');
		$host_parts = \Request::hostParts();
		$host_parts[$domain_level] = $tenant_part;
		krsort($host_parts);
		$crypt_model = new \Crypt();
		return \Request::host(['host_parts' => $host_parts]);
	}