code: def test_stimulus_mode():
      with pytest.raises(ValueError):
          s = InvertedEncoding1D(6, 5, "random")
          assert s, "Invalid InvertedEncoding1D instance"
  
imports: import pytest
  import numpy
  import logging
  from brainiak.reconstruct.iem import InvertedEncoding1D, InvertedEncoding2D
  from brainiak.utils.fmrisim import generate_1d_gaussian_rfs, generate_1d_rf_responses
  from scipy.stats import circmean
label_desc: Use image node_id 30 for calling a global function with example usage: test_stimulus_mode() without return types