code: public static function getById($relationshipId)
      {
          $key = md5($relationshipId);
          if (isset(self::$_relationships[$key])) {
              return self::$_relationships[$key];
          }
  
          return false;
      }
docs: Get by.
  
  @param [[@doctodo param_type:relationshipId]] $relationshipId [[@doctodo param_description:relationshipId]]
  
  @return [[@doctodo return_type:getById]] [[@doctodo return_description:getById]]