code: def getOpenOrders(self):
      url = "https://www.bitstamp.net/api/open_orders/"
      jsonResponse = self._post(url, {})
      return [
          Order(json_open_order) for json_open_order in jsonResponse
      ]
  
imports: import time
  import datetime
  import hmac
  import hashlib
  import requests
  import threading
  from pyalgotrade.utils import dt
  from pyalgotrade.bitstamp import common
  import logging
label_desc: Use image node_id 5 for calling the HTTPClient obj's underlying member method code with example usage: obj.getOpenOrders() and returns: unknown