code: def test_ifixx(self):
      x1 = [-2.01, -0.99, -0.001, 1.02, 1.98]
      x2 = [3.98, 1.01, 0.001, 0.998, 4.01]
      fix = np.vstack(
          (np.zeros_like(x1, dtype=int), np.ones_like(x2, dtype=int))
      )
      data = Data(np.vstack((x1, x2)), y=1, fix=fix)
      model = Model(
          lambda beta, x: x[1, :] - beta[0] * x[0, :] ** 2.0,
          implicit=True,
      )
  
      odr1 = ODR(data, model, beta0=np.array([1.0]))
      sol1 = odr1.run()
      odr2 = ODR(data, model, beta0=np.array([1.0]), ifixx=fix)
      sol2 = odr2.run()
      assert_equal(sol1.beta, sol2.beta)
  
imports: import tempfile
  import shutil
  import os
  import numpy
  from numpy import pi
  from numpy.testing import assert_array_almost_equal, assert_equal, assert_warns
  import pytest
  from pytest import raises
  from scipy.odr import Data, Model, ODR, RealData, OdrStop, OdrWarning, multilinear, exponential, unilinear, quadratic, polynomial
label_desc: Use image node_id 17 for calling the TestODR obj's underlying member method code with example usage: obj.test_ifixx() without return types