Walk from the current ledger index to the genesis ledger index,
        and download transactions from rippled.

def download(self):
        """
        Walk from the current ledger index to the genesis ledger index,
        and download transactions from rippled.
        """
        self.housekeeping()
        self.rippled_history()
        if self.resampling_frequencies is not None:
            self.find_markets()
            self.resample_time_series()