def METHOD_NAME(sheet, cols, aggrnames):
    'Add each aggregator in list of *aggrnames* to each of *cols*.'
    for aggrname in aggrnames:
        aggrs = vd.aggregators.get(aggrname)
        aggrs = aggrs if isinstance(aggrs, list) else [aggrs]
        for aggr in aggrs:
            for c in cols:
                if not hasattr(c, 'aggregators'):
                    c.aggregators = []
                if aggr and aggr not in c.aggregators:
                    c.aggregators += [aggr]