code: def test_exact(a_step_function):
      actual = np.array([a_step_function(v) for v in a_step_function.x])
      assert_array_equal(actual, a_step_function.y)
  
file_path: scikit-survival/tests/test_functions.py
imports: import numpy
  from numpy.testing import assert_array_equal
  import pytest
  from sksurv.functions import StepFunction
  from sksurv.testing import all_survival_estimators
label_desc: Use image node_id 1 for calling the TestStepFunction obj's underlying member method code with example usage: obj.test_exact(a_step_function) without return types