def serialize(self):
    r = b''
    r += struct.pack('<i', self.nVersion)
    r += ser_uint256(self.hashPrevBlock)
    r += ser_uint256(self.hashMerkleRoot)
    r += struct.pack('<I', self.nTime)
    r += struct.pack('<I', self.nufos)
    r += struct.pack('<I', self.nNonce)
    return r
def serialize(self):
    r = b
    r += struct.pack('<i', self.nVersion)
    r += ser_uint256(self.hashPrevBlock)
    r += ser_uint256(self.hashMerkleRoot)
    r += struct.pack('<I', self.nTime)
    r += struct.pack('<I', self.nufos)
    r += struct.pack('<I', self.nNonce)
    return r