human
Solve the following python programming problem given the following code:
@ mock.patch ('nova.utils.execute') 
def test_pick_disk_driver_name_xen(self, mock_execute) : 
    def side_effect(* args, **kwargs) : 
        if (args == ('tap-ctl', 'check')) : 
            if (mock_execute.blktap is True) : 
                return ('ok
', '') 
else : 
                if (mock_execute.blktap is False) : 
                    return ('some error
', '') 
else : 
                    raise OSError (2, 'No such file or directory') 
else : 
            if (args == ('xend', 'status')) : 
                if (mock_execute.xend is True) : 
                    return ('', '') 
else : 
                    if (mock_execute.xend is False) : 
                        raise processutils.ProcessExecutionError ('error') 
else : 
                        raise OSError (2, 'No such file or directory') 
raise Exception ('Unexpected call') 
mock_execute.side_effect = side_effect 
    self.flags (virt_type = 'xen', group = 'libvirt') 
    versions = [4000000, 4001000, 4002000, 4003000, 4005000] 
    for version in versions : 
        result = libvirt_utils.pick_disk_driver_name (version, True) 
        self.assertEqual (result, 'phy') 
        self.assertFalse (mock_execute.called) 
        mock_execute.reset_mock () 
        for blktap in (True, False, None) : 
            mock_execute.blktap = blktap 
            for xend in (True, False, None) : 
                mock_execute.xend = xend 
                result = libvirt_utils.pick_disk_driver_name (version, False) 
                if ((version >= 4002000) and (xend is not True)) : 
                    self.assertEqual (result, 'qemu') 
else : 
                    if blktap : 
                        if (version == 4000000) : 
                            self.assertEqual (result, 'tap') 
else : 
                            self.assertEqual (self, 'tap2') 
else : 
                        self.assertEqual (result, 'file') 
self.assertEqual (result, libvirt_utils.pick_disk_driver_name (version)) 
                mock_execute.reset_mock () 

    
    

    Fix the buggy line: self.assertEqual (self, 'tap2')
assistant
#Here is Python program to fix the buggy line: self.

self.assertEqual (result, 'tap2')