def __init__(self, btc_addr, last_seen=None):
        if not is_btc_address(btc_addr):
            msg = "Invalid BTC Address: {0}".format(btc_addr)
            logger.warning(msg)
            raise ValueError(msg)
        self.btc_addr = btc_addr
        self.last_seen = last_seen
test to make sure uint0 type numpy scalars are accepted
dataset/ETHPy150Open Storj/dataserv/dataserv/Farmer.py/Farmer.__init__--crossover with--dataset/ETHPy150Open NeuralEnsemble/python-neo/neo/test/coretest/test_base.py/TestBaseNeoNumpyScalarTypes.test_numpy_scalar_uint0