code: def orders(self, dt=None):
          
          if dt is None:
              # orders by id is already flattened
              return [o.to_dict() for o in itervalues(self._orders_by_id)]
  
          return [
              o.to_dict()
              for o in itervalues(self._orders_by_modified.get(dt, {}))
          ]
docs: Retrieve the dict-form of all of the orders in a given bar or for
          the whole simulation.
  
          Parameters
          ----------
          dt : pd.Timestamp or None, optional
              The particular datetime to look up order for. If not passed, or
              None is explicitly passed, all of the orders will be returned.
  
          Returns
          -------
          orders : list[dict]
              The order information.