code: def test_init_traces(simple_model):
      with simple_model:
          step = pm.DEMetropolisZ()
      run, traces = init_traces(
          backend=mcb.NumPyBackend(),
          chains=2,
          expected_length=70,
          step=step,
          initial_point=simple_model.initial_point(),
          model=simple_model,
      )
      assert isinstance(run, mcb.backends.numpy.NumPyRun)
      assert isinstance(traces, list)
      assert len(traces) == 2
      assert isinstance(traces[0], ChainRecordAdapter)
      assert isinstance(traces[0]._chain, mcb.backends.numpy.NumPyChain)
      pass
  
imports: import logging
  import arviz
  import numpy
  import pytest
  import pymc
  from pymc.backends import init_traces
  from pymc.step_methods.arraystep import ArrayStepShared
  from pymc.backends.mcbackend import ChainRecordAdapter, find_data, get_variables_and_point_fn, make_runmeta_and_point_fn
label_desc: Use image node_id 6 for calling a global function with example usage: test_init_traces(simple_model) without return types