code: def test_duplicate_xs(self):
      # see 2449
      # Generate cases with many duplicate x values
      x = [0] + [1] * 100 + [2] * 100 + [3]
      y = x + np.random.normal(size=len(x)) * 1e-8
      result = lowess(y, x, frac=50 / len(x), it=1)
      # fit values should be approximately averages of values at
      # a particular fit, which in this case are just equal to x
      assert_almost_equal(result[1:-1, 1], x[1:-1], decimal=7)
  
imports: import os
  import numpy
  from numpy.testing import assert_, assert_allclose, assert_almost_equal, assert_equal, assert_raises
  import pytest
  from statsmodels.nonparametric.smoothers_lowess import lowess
  import pandas
label_desc: Use image node_id 14 for calling the TestLowess obj's underlying member method code with example usage: obj.test_duplicate_xs() without return types