code: def test_StepFunction():
      x = np.arange(20)
      y = np.arange(20)
      f = utils.StepFunction(x, y)
      assert_array_almost_equal(
          f(np.array([[3.2, 4.5], [24, -3.1]])), [[3, 4], [19, 0]]
      )
  
imports: import numpy
  import pytest
  from numpy.testing import assert_array_almost_equal
  from ..None import utils
label_desc: Use image node_id 1 for calling a global function with example usage: test_StepFunction() without return types