(;
AB[qj][qm][nn][no][on][po][qo]
AW[oo][op][pp][qp][rp][mq]
C[Black plays.

Source:
    From the endgame volume of Gokyo Seimyo, a nearly 200 year old problem set.]
(;
B[ro]
C[In somewhat similar types of edge arrangements, blocking here is the best that Black can do.  But ...];
W[so]
C[... in this position, White can hane in sente.];
B[sn]
C[For example ...];
W[sp];B[rm]
C[And Black has to protect.

But Black has a better move sequence!]
)
    (;
    B[so]
    C[The tesuji!];
    W[ro]
    C[White can push here in sente, but ...];
    B[rn];W[sp]
    C[... Black can now tenuki.  White does not have a big follow-up.];
    W[sn]
    C[For example, if White captures, ...];
    B[sm]
    C[... Black can seal off the edge.

Black has given up just one stone for an entire move elsewhere.]
    )
)

