(;GM[1]FF[4]SZ[19]AP[SmartGo:0.8.7]CA[utf-8]
GN[prob_728]
AB[qk:qn][rk:sk][on][ro:rp][op:pp][or:pr]
AW[rl:rn][qo:qs][rq:sq]
C[Black plays.]
(;B[sl]
C[Destroying White's 2nd eye by simply pushing in looks good ...];W[sn]
C[... but White's block here is an unpleasant surprise.];B[sm]
C[Black captures the stones, but ...];W[so]
C[... White has this classic tesuji.];B[sp];W[rn]
C[White's under-the-stones play makes a 2nd eye.])
(;B[sn]
C[This hane is the correct move order.];W[so]
(;B[sl]
C[Now Black can push in here to create a liberty shortage.];W[sp];B[ro];W[rp]
;B[sm])
(;B[sm]
C[Note that Black does not have a double snapback here.];W[sl];B[sn];W[sp]
;B[ro];W[rp]
C[Black has nothing.])))

