(;GM[1]FF[4]AP[Drago:4.22.03]SZ[19]CA[UTF-8]AW[ss][rs][qr][rq][sq][pq][oq][or][os]AB[ns][nr][nq][no][op][pp][qp][qq][rp][sp][qs]C[Black to play and kill.]
(;B[pr]C[This looks like a snap-back shape, but is not.];W[ps])
(;B[sr]C[This also fails.];W[rr])
(;B[rr]C[This is the snap-back shape. White is defenceless.]
(;W[ps];B[sr])
(;W[sr];B[rr])))
