code: def test_default_weights():
      file_names = get_fnames("synb0_test_data")
      input_arr1 = np.load(file_names[0])["b0"][0]
      input_arr2 = np.load(file_names[0])["T1"][0]
      target_arr = np.load(file_names[1])["arr_0"][0]
  
      synb0_model = Synb0()
      synb0_model.fetch_default_weights(0)
      results_arr = synb0_model.predict(
          input_arr1, input_arr2, average=False
      )
      assert_almost_equal(results_arr, target_arr, decimal=1)
  
imports: import pytest
  from dipy.data import get_fnames
  from dipy.utils.optpkg import optional_package
  import numpy
  from numpy.testing import assert_almost_equal
label_desc: Use image node_id 1 for calling a global function with example usage: test_default_weights() without return types