public function createUserType($userType)
{
$query = "CREATE TYPE IF NOT EXISTS %s (%s)";
$fieldsString = implode(", ", array_map(function ($name, $type) {
return "{$name} " . self::typeString($type);
}, array_keys($userType->types()), $userType->types()));
$query = sprintf($query, $this->userTypeString($userType), $fieldsString);
$this->session->execute(new SimpleStatement($query));
}