code: def test_bounds_x0():
      """
      Test to check if setting bounds for signal where initial value is
      higher than subsequent values works.
  
      These values are from the IVIM dataset which can be obtained by using
      the `read_ivim` function from dipy.data.fetcher. These are values from
      the voxel [160, 98, 33] which can be obtained by :
  
      .. code-block:: python
  
         from dipy.data.fetcher import read_ivim
         img, gtab = read_ivim()
         data = load_nifti_data(img)
         signal = data[160, 98, 33, :]
  
      """
      x0_test = np.array([1.0, 0.13, 0.001, 0.0001])
      test_signal = ivim_prediction(x0_test, gtab)
  
      ivim_fit = ivim_model_trr.fit(test_signal)
  
      est_signal = ivim_fit.predict(gtab)
      assert_array_equal(est_signal.shape, test_signal.shape)
  
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 9 for calling a global function with example usage: test_bounds_x0() without return types