'Returns True if changing self.premium_type from current value to passed
in value is considered an upgrade that should trigger a re-review.'

def is_premium_type_upgrade(self, premium_type):

    ALL = set((mkt.ADDON_FREES + mkt.ADDON_PREMIUMS))
    free_upgrade = (ALL - set([mkt.ADDON_FREE]))
    free_inapp_upgrade = (ALL - set([mkt.ADDON_FREE, mkt.ADDON_FREE_INAPP]))
    if ((self.premium_type == mkt.ADDON_FREE) and (premium_type in free_upgrade)):
        return True
    if ((self.premium_type == mkt.ADDON_FREE_INAPP) and (premium_type in free_inapp_upgrade)):
        return True
    return False
