code: def getUSDAvailable(self):
      return float(self.__jsonDict["usd_available"])
  
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 3 for calling the AccountBalance obj's underlying member method code with example usage: obj.getUSDAvailable() and returns: float