/**
  * Return the number of points and abbreviation as a string.
  *
  * <code>
  * $keys = array(
  *       'user_id'   => 1,
  *       'points_id' => 2
  * );
  *
  * $userPoints  = new Gamification\User\Points\Points(JFactory::getDbo());
  * $userPoints->load($keys);
  *
  * $amount = $userPoints->__toString();
  *
  * // Alternatively
  * echo $userPoints;
  * </code>
  *
  * @return string
  */
 public function __toString()
 {
     if ($this->points !== null) {
         return $this->points_number . ' ' . $this->points->getAbbr();
     }
     return (string) $this->points_number;
 }