socketutils
~~~~~~~~~~

    socket utils:

    - recvall(s, n): recv() n bytes, otherwise raise a ValueError
    - recvtillend(s): recv() till s is disconnected
    - recvtill(s, marker): receive message ended by marker
    - recvsized(s, sizeformat='!I'): receive a sized message
    - sendsized(s, data, sizeformat='!I'): send a sized message
    - wrap_socket(s): Take an instance s of socket, and return an instance of socketutils.UtilSocket, which wraps utility functions as methods."""
