code: def get_driver(browser='firefox', args=None):
      
      if browser not in BROWSER_MAPPING.keys():
          raise RuntimeError("unknown browser %s. allowed: %s" % (browser, ", ".join(BROWSER_MAPPING.keys())))
      driver_cls = BROWSER_MAPPING.get(browser)
      safe_args = {}
      if args is not None:
          expected_arguments = inspect.getargspec(driver_cls.__init__).args
          expected_arguments.remove("self")
          for arg in expected_arguments:
              if arg in args:
                  safe_args[arg] = args[arg]
      return driver_cls(**safe_args)
docs: :param browser:
      :param args:
      :rtype: RemoteDriver
      :return: