code: def _vandermonde(x, degree):
      # Returns a matrix of monomials that span polynomials with the specified
      # degree evaluated at x.
      powers = _monomial_powers(x.shape[1], degree)
      return _rbfinterp_pythran._polynomial_matrix(x, powers)
  
imports: import pickle
  import pytest
  import numpy
  from numpy.linalg import LinAlgError
  from numpy.testing import assert_allclose, assert_array_equal
  from scipy.stats.qmc import Halton
  from scipy.spatial import cKDTree
  from scipy.interpolate._rbfinterp import _AVAILABLE, _SCALE_INVARIANT, _NAME_TO_MIN_DEGREE, _monomial_powers, RBFInterpolator
  from scipy.interpolate import _rbfinterp_pythran
label_desc: Use image node_id 1 for calling a global function with example usage: _vandermonde(x, degree) and returns: _rbfinterp_pythran