def apply_security_groups(self, security_groups):
        """
        Applies security groups to the load balancer.
        Applying security groups that are already registered with the 
        Load Balancer has no effect.

        :type security_groups: string or List of strings
        :param security_groups: The name of the security group(s) to add.

        """
        if isinstance(security_groups, str) or \
              isinstance(security_groups, unicode):
            security_groups = [security_groups]
        new_sgs = self.connection.apply_security_groups_to_lb(
                                         self.name, security_groups)
        self.security_groups = new_sgs