code: def test_prepare_error_dtype():
      t = ClinicalKernelTransform(fit_once=True)
      data = pd.DataFrame.from_dict(
          {
              "age": [12, 61, 18, 21, 57, 17],
              "date": np.array(
                  [
                      "2016-01-01",
                      "1954-06-30",
                      "1999-03-01",
                      "2005-02-25",
                      "2112-12-31",
                      "1731-09-16",
                  ],
                  dtype="datetime64",
              ),
          }
      )
  
      with pytest.raises(
          TypeError, match=r"unsupported dtype: dtype\(.+\)"
      ):
          t.prepare(data)
  
imports: import numpy
  from numpy.testing import assert_array_almost_equal
  import pandas
  import pytest
  from sklearn.base import clone
  from sklearn.metrics.pairwise import pairwise_kernels
  from sksurv.kernels import ClinicalKernelTransform, clinical_kernel
label_desc: Use image node_id 22 for calling the TestClinicalKernel obj's underlying member method code with example usage: obj.test_prepare_error_dtype() without return types