def _mle_t(n_neut, exp_rel_neut, alpha, theta):
    """ Maximum likelihood estimator for dNdS rate of neutral mutations
    """
    tml = (n_neut + alpha - 1) / (exp_rel_neut + (1/theta))

    if alpha <= 1:
        tml = max(alpha * theta, tml)

    return tml