code: def test_b0_threshold_greater_than0():
      """
      Added test case for default b0_threshold set to 50.
      Checks if error is thrown correctly.
      """
      bvals_b0t = np.array(
          [
              50.0,
              10.0,
              20.0,
              30.0,
              40.0,
              60.0,
              80.0,
              100.0,
              120.0,
              140.0,
              160.0,
              180.0,
              200.0,
              300.0,
              400.0,
              500.0,
              600.0,
              700.0,
              800.0,
              900.0,
              1000.0,
          ]
      )
      N = len(bvals_b0t)
      bvecs = generate_bvecs(N)
      gtab = gradient_table(bvals_b0t, bvecs.T)
      with assert_raises(ValueError) as vae:
          _ = IvimModel(gtab, fit_method="trr")
          b0_s = "The IVIM model requires a measurement at b==0. As of "
          assert b0_s in vae.exception
  
imports: import warnings
  import numpy
  from numpy.testing import assert_array_equal, assert_array_almost_equal, assert_raises, assert_array_less, assert_, assert_equal
  from dipy.testing import assert_greater_equal
  import pytest
  from dipy.reconst.ivim import ivim_prediction, IvimModel
  from dipy.core.gradients import gradient_table, generate_bvecs
  from dipy.sims.voxel import multi_tensor
  from dipy.utils.optpkg import optional_package
label_desc: Use image node_id 8 for calling a global function with example usage: test_b0_threshold_greater_than0() without return types