class_docstr: Abstract class w/ length-prefixed socket send/receive functions.
docstr: Send ``msg`` to destination ``sock``.
docstr_tok: ["Send","``","msg","``","to","destination","``","sock","``","."]
code: def send(self, sock, msg):
      """Send ``msg`` to destination ``sock``."""
      data = pickle.dumps(msg)
      buf = struct.pack(">I", len(data)) + data
      sock.sendall(buf)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import nested_scopes
  from __future__ import print_function
  import logging
  import os
  import pickle
  import select
  import socket
  import struct
  import sys
  import threading
  import time
  from .None import util
label_desc: Use image node_id 2 for calling the MessageSocket obj's underlying member method code with example usage: obj.send(sock, msg) without return types