code: def test_knots_not_data_sites(self, xp, scp):
      # Knots need not coincide with the data sites.
      # use a quadratic spline, knots are at data averages,
      # two additional constraints are zero 2nd derivatives at edges
      k = 2
      x, y = self.get_xy(xp)
      t = xp.r_[
          (x[0],) * (k + 1), (x[1:] + x[:-1]) / 2.0, (x[-1],) * (k + 1)
      ]
      b = scp.interpolate.make_interp_spline(
          x, y, k, t, bc_type=([(2, 0)], [(2, 0)])
      )
      return b(x), b(x[0], 2), b(x[-1], 2)
  
imports: import pytest
  import cupy
  from cupy import testing
  from cupy.cuda import runtime
  import numpy
  import cupyx.scipy.interpolate
label_desc: Use image node_id 18 for calling the TestInterp obj's underlying member method code with example usage: obj.test_knots_not_data_sites(xp, scp) and returns: b,  b,  b