code: def test_x_not_2d_error(self, xp, scp):
      y = xp.linspace(0, 1, 5)[:, None]
      x = xp.linspace(0, 1, 5)
      d = xp.zeros(5)
      self.build(scp, y, d)(x)
  
imports: import pickle
  import pytest
  import warnings
  import numpy
  from numpy.linalg import LinAlgError
  import cupy
  import cupyx
  from cupy import testing
  import cupyx.scipy.interpolate
  from cupyx.scipy.interpolate._rbfinterp import _AVAILABLE, _SCALE_INVARIANT, _NAME_TO_MIN_DEGREE, NAME_TO_FUNC, _monomial_powers, polynomial_matrix, kernel_matrix
label_desc: Use image node_id 17 for calling the _TestRBFInterpolator obj's underlying member method code with example usage: obj.test_x_not_2d_error(xp, scp) without return types