def _load(self, time_series):
        """
        Load time series into a TimeSeries object.
        :param timeseries: a TimeSeries, a dictionary or a path to a csv file(str).
        :return TimeSeries: a TimeSeries object.
        """
        if isinstance(time_series, TimeSeries):
            return time_series
        if isinstance(time_series, dict):
            return TimeSeries(time_series)
        return TimeSeries(utils.read_csv(time_series))