Set the serialiser to use for a format
string $class The name of the class:
public function setSerialiserClass($class) {
  if ($class) {
    if (!is_string($class)) {
      throw new InvalidArgumentException("\$class should be a string");
    }
    $this->serialiserClass = $class;
  }
  else {
    $this->serialiserClass = null;
  }
}