> Before
:g1:a -> :g2:a
:g3:a -> :g4:a
:g5:a -> :g6:a
:g7:a -> :g8:a
> After
:g1:a -> :g2
:g1:a -> :g2:a
:g3:a -> :g4:a
:g3 -> :g4:a
:g5 -> :g6:a
:g7:a -> :g8
