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static ulong encode(string msg)
{
    ulong x = BitConverter.ToUInt64(Encoding.ASCII.GetBytes(msg), 0);
    x = foo(x, 0x000000003a229013, 32);
    x = foo(x, 0x00002fb000009e23, 16);
    x = foo(x, 0x00c10061005400c2, 8);
    x = foo(x, 0x0e0e05070b020902, 4);
    x = foo(x, 0x1002200011133031, 2);
    x = foo(x, 0x1114544041540141, 1);
    x = foo(x, 0x2100022031313022, 2);
    x = foo(x, 0x0c0d08070f070506, 4);
    x = foo(x, 0x002c004c001b001f, 8);
    x = foo(x, 0x00001d670000fc2f, 16);
    x = foo(x, 0x000000001cf1aa86, 32);
    return x;
}

static ulong foo(ulong x, ulong m, int k)
{
    ulong t = ((x >> k) ^ x) & m;
    x = (x ^ t) ^ (t << k);
    return x;
}

public static IEnumerable<IList<T>> Split<T>(this IEnumerable<T> collection,T delim,IEqualityComparer<T> equalityComparer = null) // ...

public static IEnumerable<T> Join<T>(this IEnumerable<IList<T>> segments, IEnumerable<T> delim) // ...

public static IEnumerable<T> Replace<T>(this IEnumerable<T> collection,T oldValue, IEnumerable<T> newValues, IEqualityComparer<T> equalityComparer = null) // ...