code: def test_zerocross(self):
      np.testing.assert_almost_equal(zero_cross(const0), 0.0)
      np.testing.assert_almost_equal(zero_cross(const1), 0.0)
      np.testing.assert_almost_equal(zero_cross(constNeg), 0.0)
      np.testing.assert_almost_equal(zero_cross(constF), 0.0)
      np.testing.assert_almost_equal(zero_cross(lin), 1.0)
      np.testing.assert_almost_equal(zero_cross(lin0), 1.0, decimal=5)
      np.testing.assert_almost_equal(zero_cross(wave), 10, decimal=5)
      np.testing.assert_almost_equal(
          zero_cross(offsetWave), 0.0, decimal=5
      )
      np.testing.assert_almost_equal(
          zero_cross(noiseWave), 38, decimal=5
      )
  
imports: import unittest
  import numpy
  from tsfel.feature_extraction.features import *
label_desc: Use image node_id 27 for calling the TestFeatures obj's underlying member method code with example usage: obj.test_zerocross() without return types