code: def test_splder_vs_splev(self):
      # Check derivative vs. FITPACK
  
      for n in range(3 + 1):
          # Also extrapolation!
          xx = np.linspace(-1, 2, 2000)
          if n == 3:
              # ... except that FITPACK extrapolates strangely for
              # order 0, so let's not check that.
              xx = xx[(xx >= 0) & (xx <= 1)]
  
          dy = splev(xx, self.spl, n)
          spl2 = splder(self.spl, n)
          dy2 = splev(xx, spl2)
          if n == 1:
              assert_allclose(dy, dy2, rtol=2e-6)
          else:
              assert_allclose(dy, dy2)
  
imports: import itertools
  import os
  import numpy
  from numpy.testing import assert_equal, assert_allclose, assert_, assert_almost_equal, assert_array_almost_equal
  from pytest import raises
  import pytest
  from scipy._lib._testutils import check_free_memory
  from scipy.interpolate import RectBivariateSpline
  from scipy.interpolate._fitpack_py import splrep, splev, bisplrep, bisplev, sproot, splprep, splint, spalde, splder, splantider, insert, dblint
  from scipy.interpolate.dfitpack import regrid_smth
  from scipy.interpolate._fitpack2 import dfitpack_int
label_desc: Use image node_id 3 for calling the TestSplder obj's underlying member method code with example usage: obj.test_splder_vs_splev() without return types