def get_profile_ids(self, activity_id, since=None):
        ids = []

        #If there is a since param return all profileIds since then
        if since:
            try:
                # this expects iso6801 date/time format "2013-02-15T12:00:00+00:00"
                profs = ActivityProfile.objects.filter(updated__gte=since, activity_id=activity_id)
            except __HOLE__:
                err_msg = 'Since field is not in correct format for retrieval of activity profile IDs'
                raise ParamError(err_msg) 
            ids = [p.profile_id for p in profs]
        else:
            #Return all IDs of profiles associated with this activity b/c there is no since param
            ids = ActivityProfile.objects.filter(activity_id=activity_id).values_list('profile_id', flat=True)
        return ids
dataset/ETHPy150Open adlnet/ADL_LRS/lrs/managers/ActivityProfileManager.py/ActivityProfileManager.get_profile_ids