code: def browser(tags=None, proxy=None, other_caps=None):
      browser_name = os.environ.get('SELENIUM_BROWSER', 'firefox')
      def browser_check_func():
          try:
              if _use_remote_browser(SAUCE_ENV_VARS):
                  browser_class, browser_args, browser_kwargs = _remote_browser_class(
                      SAUCE_ENV_VARS, tags)
              elif _use_remote_browser(REMOTE_ENV_VARS):
                  browser_class, browser_args, browser_kwargs = _remote_browser_class(
                      REMOTE_ENV_VARS, tags)
              else:
                  browser_class, browser_args, browser_kwargs = _local_browser_class(
                      browser_name)
              if proxy:
                  browser_kwargs = _proxy_kwargs(browser_name, proxy, browser_kwargs)
              if browser_class == webdriver.Remote:
                  desired_caps = other_caps or {}
                  desired_caps.update(browser_kwargs.get('desired_capabilities', {}))
                  browser_kwargs['desired_capabilities'] = desired_caps
              return True, browser_class(*browser_args, **browser_kwargs)
          except (socket.error, WebDriverException) as err:
              msg = str(err)
              LOGGER.debug('Failed to instantiate browser: ' + msg)
              return False, None
      browser_instance = Promise(
          browser_check_func, "Browser is instantiated successfully.", try_limit=3, timeout=95).fulfill()
      return browser_instance