/**
  * Set the currently active configuration object
  * @param $identifier string - the identifier for the config set
  * @return null
  */
 public static function set_active($identifier = null)
 {
     self::$current = $identifier;
 }
 /**
  * Set the currently active configuration object. Note that the existing active
  * config will not be renamed to the new identifier.
  *
  * @param string $identifier The identifier for the config set
  */
 public static function set_active_identifier($identifier)
 {
     self::$current = $identifier;
 }