test.py

class TCPStream:
    ...

    def __iter__ (self):
        """
            Read lines of input from the socket.

            Yields strings without trailing newlines.

            Returns on EOF.
        """

        while True:
            try:
                buf = yield from self.readline()
            except EOFError:
                return

            line = buf.rstrip(b'\n').decode(self.encoding)

            # XXX: crazy abuse 
            yield line

@asyncio.coroutine
def client (tcp_stream):
    """
        tcp_stream:     TCPStream
    """
    for line in tcp_stream:
        if isinstance(line, asyncio.Future):
            log.debug("%s: yield ->", tcp_stream)
            yield from line
            log.debug("%s: yield <-", tcp_stream)
            continue

        log.info("%s: %s", tcp_stream, line)

    log.info("%s: eof", tcp_stream)