(;
AB[pc][pd][nd][ne][rd][qe][pf][pj]
AW[nc][oc][md][re][rf][qf][ng][pg]
C[Black plays.

Source:
    "American Go Journal", v35,n1 
    Adapted from "Go Review", May 1970, Rin Kaiho's "Go Achievement Test"]
(;
B[me]
C[Black must run out to avoid being sealed into the corner, but this push is a mistake.];
W[ld];B[le];W[kd];B[lg]
C[Black runs out simply and successfully, but suffers a great loss by strengthening White's top.]
)
    (;
    B[mf]
    C[Much better.  Black runs out, but ...];
    W[kc]
    C[... White must defend at the top, because of the weakness at A.  In addition, White's top is weaker than in the previous variation.

Can the reader now see how Black should use sente to follow up?]
    LB[mc:A]
    PL[W]
    (;
    B[ob]
    C[Correct.  After escaping out to the center, Black secures the corner.]
    )
        (;
        W[rc]
        C[If Black tenukis, White can snatch the corner here.];
        B[sd];W[qc];B[qd];W[pb]
        )
    )
)

