How to use the pandasticsearch.operators.Grouper function in pandasticsearch

def from_list(l):
        if len(l) == 1:
            return Grouper(l[0])
        return Grouper(l[0], inner=Grouper.from_list(l[1:]))

if self._exclude is not None:
            assert isinstance(self._exclude, list)
            terms['exclude'] = self._exclude
        if self._include is not None:
            assert isinstance(self._include, list)
            terms['include'] = self._include

        agg = {"terms": terms}

        if self._inner is not None:
            agg["aggregations"] = self._inner.build()

        return {self._field: agg}


class RangeGrouper(Grouper):
    def __init__(self, field, range_list):
        assert isinstance(range_list, list)
        super(RangeGrouper, self).__init__(field)
        self._field = field
        self._range_list = range_list

    def build(self):
        ranges = []
        starts = self._range_list[:-1]
        ends = self._range_list[1:]
        for start, end in zip(starts, ends):
            ranges.append({'from': start, 'to': end})

        name = 'range(' + ','.join([str(x) for x in self._range_list]) + ')'
        return {name: {'range': {'field': self._field, 'ranges': ranges}}}

super(RangeGrouper, self).__init__(field)
        self._field = field
        self._range_list = range_list

    def build(self):
        ranges = []
        starts = self._range_list[:-1]
        ends = self._range_list[1:]
        for start, end in zip(starts, ends):
            ranges.append({'from': start, 'to': end})

        name = 'range(' + ','.join([str(x) for x in self._range_list]) + ')'
        return {name: {'range': {'field': self._field, 'ranges': ranges}}}


class DateGrouper(Grouper):
    def __init__(self, field, interval, format):
        super(DateGrouper, self).__init__(field)
        self._field = field
        self._interval = interval
        self._format = format

    def build(self):
        name = 'date({0},{1})'.format(self._field, self._interval)
        return {name: {'date_histogram': {
            'field': self._field,
            'interval': self._interval,
            'format': self._format,
        }}}


class Scriptor(object):

def from_list(l):
        if len(l) == 1:
            return Grouper(l[0])
        return Grouper(l[0], inner=Grouper.from_list(l[1:]))