(;
AB[np][nq][nr][pp][qp][rp][os]
AW[qk][qn][ro][kq][mq][mr][ms][ns]
C[Black's response to the marked connection?

Source:
    From the endgame volume of Gokyo Seimyo, a nearly 200 year old problem set.]
TR[ms]
(;
B[rr]
C[Correct.  Black simultaneously protects both the bottom and right edges.  If White A, Black can block with B without having to protect a cut.]
LB[sp:A][sq:B];
W[or]
C[And if White insists ...];
B[ps];W[pr];B[qs];W[qr];B[rs]
C[... and White has nothing.]
)
    (;
    B[pr]
    C[Slack.  Black protects the cut, but ...];
    W[sp]
    C[... now White has a 2nd sente hane.];
    B[sq];W[so];B[rq]
    C[White has reduced both sides of Black's corner in sente.]
    )
)

