code: def test_endslopes(self):
      # this is a smoke test for gh-3453: PCHIP interpolator should not
      # set edge slopes to zero if the data do not suggest zero edge derivatives
      x = np.array([0.0, 0.1, 0.25, 0.35])
      y1 = np.array([279.35, 0.5e3, 1.0e3, 2.5e3])
      y2 = np.array([279.35, 2.5e3, 1.50e3, 1.0e3])
      for pp in (pchip(x, y1), pchip(x, y2)):
          for t in (x[0], x[-1]):
              assert_(pp(t, 1) != 0)
  
imports: import warnings
  import io
  import numpy
  from numpy.testing import assert_almost_equal, assert_array_equal, assert_array_almost_equal, assert_allclose, assert_equal, assert_
  from pytest import raises
  from scipy.interpolate import KroghInterpolator, krogh_interpolate, BarycentricInterpolator, barycentric_interpolate, approximate_taylor_polynomial, CubicHermiteSpline, pchip, PchipInterpolator, pchip_interpolate, Akima1DInterpolator, CubicSpline, make_interp_spline
label_desc: Use image node_id 6 for calling the TestPCHIP obj's underlying member method code with example usage: obj.test_endslopes() without return types