code: def test_ws_roundtrip():
      pytest.importorskip("websockets")
      s0 = Stream.from_websocket("localhost", 8989, start=True)
      l = s0.sink_to_list()
  
      data = [b"0123"] * 4
      s = Stream.from_iterable(data)
      s.to_websocket("ws://localhost:8989")
      s.start()
  
      wait_for(lambda: data == l, timeout=1)
      s.stop()
      s0.stop()
  
file_path: streamz/streamz/tests/test_sinks.py
imports: import weakref
  import pytest
  from streamz import Stream
  from streamz.sinks import _global_sinks, Sink
  from streamz.utils_test import tmpfile, wait_for
label_desc: Use image node_id 6 for calling a global function with example usage: test_ws_roundtrip() without return types