gistfile1.txt

import asyncio


class A:
    def __init__(self, reader, writter):
        self.reader, self.writer = reader, writter

    @asyncio.coroutine
    def read_packet(self):
        bsize = yield from self.reader.readexactly(4)
        size = int(bsize)
        data = yield from self.reader.readexactly(size)
        return data

    @coroutine
    @classmethod
    def connect(cls, host, port):
        reader, writter = yield from asyncio.open_connection(host, port)
        return cls(reader, writer)


@coroutine
def go():
    a = yield from A.connect('localhost', 5555)

    data = yield from a.read_packet()