(;SZ[19]AW[bb]AW[eb]AW[cc]AW[bd]AW[ae]AW[be]AB[fb]AB[dc]AB[ec]AB[fc]AB[cd]AB[ce]AB[bf]AB[cf]AB[bh]
(;B[cb]
(;W[bc]C[CHOICE]
(;B[ba];W[db]
(;B[ca];W[ab]
(;B[ea]C[RIGHT])
(;B[da]C[RIGHT]))
(;B[da]C[just a ko]))
(;B[db];W[ba])
(;B[ca];W[ba]))
(;W[ac]C[CHOICE]LB[bc:Ko?]
(;B[ba];W[db]LB[bc:Ko?]
(;B[ca];W[aa]
(;B[bc]C[double koRIGHT])
(;B[ab]C[double koRIGHT])
(;B[ea];W[da]))
(;B[bc]C[Ko is not enough.]))
(;B[bc]C[Ko is not enough.])))
(;B[db];W[cb]
(;B[ac];W[ab];B[ca];W[ba])
(;B[ca];W[ba];B[ac];W[ab]))
(;B[ba];W[cb])
(;B[ac];W[ab]
(;B[cb];W[bc];B[ba];W[db]
(;B[ca];W[aa])
(;B[da]C[only ko]))
(;B[db];W[cb];B[ca];W[ba])
(;B[bc];W[cb]))
(;B[ab];W[ac])
(;B[bc];W[ac];B[cb];W[db])
(;B[ad];W[ac];B[cb];W[db])
(;B[ca];W[ba]
(;B[cb];W[bc])
(;B[ac];W[ab]
(;B[bc];W[cb])
(;B[cb];W[bc]))
(;B[bc];W[ac])))