private static UInt32 Mur(UInt32 a, UInt32 h)
 {
     // Helper from Murmur3 for combining two 32-bit values.
     a *= c1;
     a = a.RotateRight(17);
     a *= c2;
     h ^= a;
     h = h.RotateRight(19);
     return h * 5 + 0xe6546b64;
 }