code: def test_wait_for_events(ctx_factory):
      ctx = ctx_factory()
      queue = cl.CommandQueue(ctx)
      evt1 = cl.enqueue_marker(queue)
      evt2 = cl.enqueue_marker(queue)
      cl.wait_for_events([evt1, evt2])
  
imports: import numpy
  import numpy.linalg
  import pytest
  import pyopencl
  import pyopencl.array
  import pyopencl.cltypes
  import pyopencl.clrandom
  from pyopencl.tools import pytest_generate_tests_for_pyopencl, ImmediateAllocator, DeferredAllocator
  from pyopencl.characterize import get_pocl_version
label_desc: Use image node_id 22 for calling a global function with example usage: test_wait_for_events(ctx_factory) without return types