Prepare load balancer variables

def _prepare_load_balancers(self):
        """
        Prepare load balancer variables
        """
        stack = {
                A.NAME: self[A.NAME],
                A.VERSION: self[A.VERSION],
                }

        for load_balancer in self.get(R.LOAD_BALANCERS, []):
            svars = {A.STACK: stack}
            load_balancer[A.loadbalancer.VARS] = svars