<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def wait_for_browser_close(b):
 """ Can be used to wait until a TBrowser is closed """

    if b:
        if not __ACTIVE:
            wait_failover(wait_for_browser_close)
            return
        wait_for_frame(b.GetBrowserImp().GetMainFrame())