def _uchain(*args):
    sent = set()
    for i in chain(*args):
        if i not in sent:
            yield i
            sent.add(i)
Creates a TCP server socket which listens on `port` number.
dataset/ETHPy150Open sqlboy/fileseq/test/run.py/_uchain--crossover with--dataset/ETHPy150Open osrg/ryu/ryu/services/protocols/bgp/base.py/Activity._listen_tcp