code: def test_qhull_triangle_orientation():
      # github issue 4437.
      xi = np.linspace(-2, 2, 100)
      x, y = map(np.ravel, np.meshgrid(xi, xi))
      w = (x > y - 1) & (x < -1.95) & (y > -1.2)
      x, y = x[w], y[w]
      theta = np.radians(25)
      x1 = x * np.cos(theta) - y * np.sin(theta)
      y1 = x * np.sin(theta) + y * np.cos(theta)
  
      # Calculate Delaunay triangulation using Qhull.
      triang = mtri.Triangulation(x1, y1)
  
      # Neighbors returned by Qhull.
      qhull_neighbors = triang.neighbors
  
      # Obtain neighbors using own C++ calculation.
      triang._neighbors = None
      own_neighbors = triang.neighbors
  
      assert_array_equal(qhull_neighbors, own_neighbors)
  
imports: import numpy
  from numpy.testing import assert_array_equal, assert_array_almost_equal, assert_array_less
  import numpy.ma.testutils
  import pytest
  import matplotlib
  import matplotlib.pyplot
  import matplotlib.tri
  from matplotlib.path import Path
  from matplotlib.testing.decorators import image_comparison, check_figures_equal
label_desc: Use image node_id 29 for calling a global function with example usage: test_qhull_triangle_orientation() without return types