code: def simple_sell(quote_ctx, trade_ctx, stock_code, trade_price, volume, trade_env, order_type=ft.OrderType.SPECIAL_LIMIT):
      
      lot_size = 0
      while True:
          sleep(0.1)
          if lot_size == 0:
              ret, data = quote_ctx.get_market_snapshot(stock_code)
              lot_size = data.iloc[0]['lot_size'] if ret == ft.RET_OK else 0
              if ret != ft.RET_OK:
                  print("can't get lot size, retrying: {}".format(data))
                  continue
              elif lot_size <= 0:
                  raise Exception('lot size error {}:{}'.format(lot_size, stock_code))
  
          qty = int(volume // lot_size) * lot_size
          ret, data = trade_ctx.place_order(price=trade_price, qty=qty, code=stock_code,
                                            trd_side=ft.TrdSide.SELL, trd_env=trade_env, order_type=order_type)
          if ret != ft.RET_OK:
              print('下单失败:{}'.format(data))
              return None
          else:
              print('下单成功')
              return data
docs: 简单卖出函数