(;
AB[lo][mo][mp][op][pp][kq][kr][lq][nq][pq][qq][or]
AW[no][oo][po][qo][np][qp][mq][mr][rq][rr][nr]
PL[W]
C[White plays.]
(;
W[oq]
C[Of course, White has at least this ko.  But does White have anything better?]
)
    (;
    W[qr]
    C[Forcing.];
    B[pr]
    (;
    W[ps]
    C[Does this hane do any better than a direct ko?];
    B[os];W[ns];B[qs]
    C[Black only has a 2 step ko.  So this result is a bit better for White than the main line's direct ko.

But can White do even better?]
    )
        (;
        W[os]
        C[At first glance, the hane on this side may seem the same as the previous hane, but ...];
        B[ps];W[qs];B[ns];W[ms]
        C[... amazingly, with this blocking descent, White lives outright with a double ko!]
        )
    )
)

