/**
  * Returns an instance of class
  *
  * @return MEMBERSHIP_BOL_MembershipTypeDao
  */
 public static function getInstance()
 {
     if (self::$classInstance === null) {
         self::$classInstance = new self();
     }
     return self::$classInstance;
 }
 public function deleteUserMembershipsByRoleId($roleId)
 {
     $types = $this->membershipTypeDao->getTypeIdListByRoleId($roleId);
     if ($types) {
         foreach ($types as $typeId) {
             $this->membershipUserDao->deleteByTypeId($typeId);
         }
     }
     return true;
 }