@classmethod
def _enforce_min_commissions(cls, commissions, nlvs):
    """
        Return a DataFrame of commissions after enforcing the min commission.
        """
    min_commissions = cls.MIN_COMMISSION / nlvs
    must_pay_min_commissions = (commissions > 0) & (commissions <
        min_commissions)
    commissions = commissions.where(must_pay_min_commissions == False,
        min_commissions)
    return commissions
