'Kill a window and check that qtile unmaps it
Kills a window created by calling one of the `self.test*` methods,
ensuring that qtile removes it from the `windows` attribute.'

def kill_window(self, proc):

    assert (proc in self.testwindows), 'Given    process    is    not    a    spawned    window'
    start = len(self.c.windows())
    proc.terminate()
    proc.wait()
    self.testwindows.remove(proc)
    @retry(ignore_exceptions=(ValueError,))
    def success():
        if (len(self.c.windows()) < start):
            return True
        raise ValueError('window    is    still    in    client    list!')
    if (not success()):
        raise AssertionError('Window    could    not    be    killed...')
