(;GM[1]FF[4]AP[Drago:4.22.03]SZ[19]CA[UTF-8]AB[sr][rq][qr][ps][pq][oq][nq][nr][ns]AW[ms][mr][mq][op][np][mp][pp][qp][qq][or][ro][so][rr][rs]C[Black to play and live.]
(;B[qs]C[This is incorrect.];W[sq]
(;B[ss];W[rr];B[sp];W[rp]
;B[rs]C[Black has to win the ko to live.];W[sq])
(;B[sp]C[This leads to the same result.]))
(;B[sq]C[This is correct.];W[pr];B[os]
;W[pr]C[This looks like it causes Black to run out of liberties.];B[ss]C[However this creates a snap-back shape.];W[qs]
;B[qr]C[Black lives.]))
