'High level function which returns :
curve(2) + len_of_pubkeyX(2) + pubkeyX + len_of_pubkeyY + pubkeyY'

def get_pubkey(self):

    return ''.join((pack('!H', self.curve), pack('!H', len(self.pubkey_x)), self.pubkey_x, pack('!H', len(self.pubkey_y)), self.pubkey_y))
