Press down Alt, then press n times Tab, then release Alt.

def AltTab(self, n=1, delay=0):
        """Press down Alt, then press n times Tab, then release Alt.
        """
        self._delay(delay)
        self.add(Command("KeyDown", 'KeyDown "%s", %s' % (BoardKey.Alt, 1)))
        for i in range(n):
            self.add(Command("KeyPress", 'KeyPress "%s", %s' % (BoardKey.Tab, 1)))
        self.add(Command("KeyUp", 'KeyUp "%s", %s' % (BoardKey.Alt, 1)))