An unsigned 256 bit value that can be used to encode a nonce into a distinct space.
Sequential number starting at 0, and incrementing in single steps e.g. 0,1,2,...
The encoded value where the space is left shifted 96 bits, and the nonce is in the first 96 bits.
This helper function is used to encode the nonce into a 256 bit value where the space is encoded into the first 160 bits, and the nonce the remaining 96 bits.