'After cleaned, return a list of ints for the constants.'

def clean_premium_types(self):

    pt_ids = []
    for pt in self.cleaned_data.get('premium_types'):
        pt_id = mkt.ADDON_PREMIUM_API_LOOKUP.get(pt)
        if (pt_id is not None):
            pt_ids.append(pt_id)
    if pt_ids:
        return pt_ids
