class_docstr: Terminates once it receives the first ping() call.
code: def __init__(self):
      self._server = None  # type: courier.Server
      self._has_ping = threading.Event()
      self._has_call = threading.Event()
  
imports: import datetime
  import sys
  import threading
  import time
  from unittest import mock
  from absl.testing import absltest
  import courier
  from launchpad.launch.test_multi_threading import address_builder
  from launchpad.nodes.courier import node
label_desc: Use image node_id 1 to create a new Server object from inherited base classes: object with example: obj = Server()