code: def batch_market_order(self, share_counts):
          
          style = MarketOrder()
          order_args = [
              (asset, amount, style)
              for (asset, amount) in iteritems(share_counts)
              if amount
          ]
          return self.blotter.batch_order(order_args)
docs: Place a batch market order for multiple assets.
  
          Parameters
          ----------
          share_counts : pd.Series[Asset -> int]
              Map from asset to number of shares to order for that asset.
  
          Returns
          -------
          order_ids : pd.Index[str]
              Index of ids for newly-created orders.