class_docstr: Used for serialization/deserialization of objects over the wire.
  
  We use HMAC to protect services from unauthorized use. The key used for
  the HMAC digest is distributed by Open MPI and Spark.
  
  The objects are serialized using cloudpickle. Serialized objects become
  the body of the message.
  
  Structure of the message is as follows:
  - HMAC digest of the body (32 bytes)
  - length of the body (4 bytes)
  - body
code: def __init__(self, key):
      self._key = key
  
imports: import random
  import socket
  import struct
  import threading
  import cloudpickle
  import psutil
  from six.moves import queue, socketserver
  from bluefog.run.horovodrun.common.util import secret
label_desc: Use image node_id 1 to create a new Wire object from inherited base classes: object with example: obj = Wire(key)