code: def test_show():
      """Test mpld3.show() using a mock server"""
  
      class MockRequest(object):
          def makefile(self, *args, **kwargs):
              return IO(b"GET /")
  
          def sendall(self, b):
              pass
  
      class MockServer(object):
          def __init__(self, ip_port, Handler):
              handler = Handler(MockRequest(), ip_port[0], self)
  
          def serve_forever(self):
              pass
  
          def server_close(self):
              pass
  
      # Any exceptions in the show() routine will pop up here
      plt.plot([1, 2, 3])
      show(open_browser=False, http_server=MockServer)
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_show() and returns: IO