code: def test_fiedler():
      f = fiedler([])
      assert_equal(f.size, 0)
      f = fiedler([123.0])
      assert_array_equal(f, np.array([[0.0]]))
      f = fiedler(np.arange(1, 7))
      des = np.array(
          [
              [0, 1, 2, 3, 4, 5],
              [1, 0, 1, 2, 3, 4],
              [2, 1, 0, 1, 2, 3],
              [3, 2, 1, 0, 1, 2],
              [4, 3, 2, 1, 0, 1],
              [5, 4, 3, 2, 1, 0],
          ]
      )
      assert_array_equal(f, des)
  
imports: import pytest
  import numpy
  from numpy import arange, array, eye, copy, sqrt
  from numpy.testing import assert_equal, assert_array_equal, assert_array_almost_equal, assert_allclose
  from pytest import raises
  from scipy.fft import fft
  from scipy.special import comb
  from scipy.linalg import toeplitz, hankel, circulant, hadamard, leslie, dft, companion, kron, block_diag, helmert, hilbert, invhilbert, pascal, invpascal, fiedler, fiedler_companion, eigvals, convolution_matrix
  from numpy.linalg import cond
label_desc: Use image node_id 3 for calling a global function with example usage: test_fiedler() without return types