(;
AB[lo][mp][op][pp][qp][rp][sp][lq][lr][ls][qq][or][pr]
AW[mq][nq][oq][pq][rq][rr][sq][mr][ms][qr]
PL[W]
C[White plays.]
(;
W[qs]
C[A mistake.]
(;
B[ns];W[ss]
C[White lives in gote, but loses the left half of the group outright.]
)
    (;
    B[ss]
    C[An overplay.];
    W[ps]
    C[White saves all the stones.]
    )
)
    (;
    W[os]
    C[Better.];
    B[ps];W[nr]
    C[Ko.  Losing the ko, White can still live with the right half of the group.  But winning the ko, White saves all the stones and even captures 3 stones.]
    )
)

