code: def order_target(self,
                       asset,
                       target,
                       limit_price=None,
                       stop_price=None,
                       style=None):
          
          if not self._can_order_asset(asset):
              return None
  
          amount = self._calculate_order_target_amount(asset, target)
          return self.order(asset, amount,
                            limit_price=limit_price,
                            stop_price=stop_price,
                            style=style)
docs: Place an order to adjust a position to a target number of shares. If
          the position doesn't already exist, this is equivalent to placing a new
          order. If the position does exist, this is equivalent to placing an
          order for the difference between the target number of shares and the
          current number of shares.
  
          Parameters
          ----------
          asset : Asset
              The asset that this order is for.
          target : int
              The desired number of shares of ``asset``.
          limit_price : float, optional
              The limit price for the order.
          stop_price : float, optional
              The stop price for the order.
          style : ExecutionStyle
              The execution style for the order.
  
          Returns
          -------
          order_id : str
              The unique identifier for this order.
  
  
          Notes
          -----
          ``order_target`` does not take into account any open orders. For
          example:
  
          .. code-block:: python
  
             order_target(sid(0), 10)
             order_target(sid(0), 10)
  
          This code will result in 20 shares of ``sid(0)`` because the first
          call to ``order_target`` will not have been filled when the second
          ``order_target`` call is made.
  
          See :func:`zipline.api.order` for more information about
          ``limit_price``, ``stop_price``, and ``style``
  
          See Also
          --------
          :class:`zipline.finance.execution.ExecutionStyle`
          :func:`zipline.api.order`
          :func:`zipline.api.order_target_percent`
          :func:`zipline.api.order_target_value`