problem taken from tesuji by james davies, ch. 14 ignore the atari...
(;AB[rb]AB[qb]AB[qc]AB[pd]AB[oc]AB[oe]AB[pf]AB[qi]AW[rc]AW[qd]AW[qe]AW[qf]AW[qg]AW[pe]AW[of]AP[goproblems]
(;B[nf];W[og]C[even if black plays a defensive move at A he loses senteCHOICE]LB[me:A])
(;B[ne]C[RIGHT];W[og]LB[mg:A]C[black keeps sente by playing here at ARIGHT]))