Reads the audit log

        Parameters
        ----------
        symbol: str
            optionally only retrieve specific symbol's audit information

        Returns
        -------
        list of dicts

def read_audit_log(self, symbol=None):
        """
        Reads the audit log

        Parameters
        ----------
        symbol: str
            optionally only retrieve specific symbol's audit information

        Returns
        -------
        list of dicts
        """
        if symbol:
            return [x for x in self._audit.find({'symbol': symbol}, {'_id': False})]
        return [x for x in self._audit.find({}, {'_id': False})]