{
    /(b_xor)
        (bA)(bB)
            /(zqA)(lbA)(hb!A)
                /
                    /(zqB)(lbB)(hb!B)
                        /
                            /
                                /[hb!B]/[hb!A][b_xor]
                            /
                                /[lbB]/[lbA][xor]
                            [b!]
                        /
                            [bA]
                        [zqB]
                    [bB]
                /
                    [bB]
                [zqA]
            [bA]
    [YC]
|
    b_xor
}