code: def test_periodic_eval(self):
      x = np.linspace(0, 2 * np.pi, 10)
      y = np.cos(x)
      S = CubicSpline(x, y, bc_type="periodic")
      assert_almost_equal(S(1), S(1 + 2 * np.pi), decimal=15)
  
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 5 for calling the TestCubicSpline obj's underlying member method code with example usage: obj.test_periodic_eval() without return types