Retrieve the dict-form of all of the transactions in a given bar or
        for the whole simulation.

        Parameters
        ----------
        dt : pd.Timestamp or None, optional
            The particular datetime to look up transactions for. If not passed,
            or None is explicitly passed, all of the transactions will be
            returned.

        Returns
        -------
        transactions : list[dict]
            The transaction information.

def transactions(self, dt=None):
        """Retrieve the dict-form of all of the transactions in a given bar or
        for the whole simulation.

        Parameters
        ----------
        dt : pd.Timestamp or None, optional
            The particular datetime to look up transactions for. If not passed,
            or None is explicitly passed, all of the transactions will be
            returned.

        Returns
        -------
        transactions : list[dict]
            The transaction information.
        """
        if dt is None:
            # flatten the by-day transactions
            return [
                txn
                for by_day in itervalues(self._processed_transactions)
                for txn in by_day
            ]

        return self._processed_transactions.get(dt, [])