code: def test_from_iterable_backpressure():
      it = iter(range(5))
      source = Source.from_iterable(it)
      L = source.rate_limit(0.1).sink_to_list()
      source.start()
  
      wait_for(lambda: L == [0], 1, period=0.01)
      assert next(it) == 2
  
file_path: streamz/streamz/tests/test_sources.py
imports: import asyncio
  import sys
  from flaky import flaky
  import pytest
  from streamz import Source
  from streamz.utils_test import wait_for, await_for, gen_test
  import socket
label_desc: Use image node_id 8 for calling a global function with example usage: test_from_iterable_backpressure() without return types