def nll_has_variance(nll_str):
    """ A simple helper to return whether we have variance in the likelihood.

    :param nll_str: the type of negative log-likelihood.
    :returns: true or false
    :rtype: bool

    """
    nll_map = {
        'gaussian': True,
        'laplace': True,
        'pixel_wise': False,
        'l2': False,
        'msssim': False,
        'bernoulli': False,
        'l2msssim': False,
        'log_logistic_256': True,
        'disc_mix_logistic': True
    }

    assert nll_str in nll_map
    return nll_map[nll_str]