code: def test_small_dx(self):
      rng = np.random.RandomState(0)
      x = np.sort(rng.uniform(size=100))
      y = 1e4 + rng.uniform(size=100)
      S = CubicSpline(x, y)
      self.check_correctness(S, tol=1e-13)
  
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 9 for calling the TestCubicSpline obj's underlying member method code with example usage: obj.test_small_dx() without return types