def METHOD_NAME(data, alpha, est_sigma, tail):
    if tail:
        return r(
            'mack<-MackChainLadder({},alpha={}, est.sigma="{}", tail=TRUE)'.format(
                data, alpha, est_sigma
            )
        )
    else:
        return r(
            'mack<-MackChainLadder({},alpha={}, est.sigma="{}")'.format(
                data, alpha, est_sigma
            )
        )