code: def test_shape():
      """
      Test if `shape` in `IvimFit` class gives the correct output.
      """
      assert_array_equal(ivim_fit_single.shape, ())
      ivim_fit_multi = ivim_model_trr.fit(data_multi)
      assert_array_equal(ivim_fit_multi.shape, (2, 2, 1))
  
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 12 for calling a global function with example usage: test_shape() without return types