code: def test_surf_guassians():
      f = np.zeros((1024, 1024))
      Y, X = np.indices(f.shape)
      Y -= 768
      X -= 768
      f += 120 * np.exp(-(Y**2) / 2048.0 - X**2 / 480.0)
      Y += 512
      X += 512
      f += 120 * np.exp(-(Y**2) / 2048.0 - X**2 / 480.0)
      spoints = surf.surf(f, 1, 24, 2)
  
      YX = np.array([spoints[:, 0], spoints[:, 1]]).T
      is_256 = False
      is_768 = False
      for y, x in YX:
          if np.abs(y - 256) < 8 and np.abs(x - 256) < 8:
              is_256 = True
          if np.abs(y - 768) < 8 and np.abs(x - 768) < 8:
              is_768 = True
      assert is_256
      assert is_768
  
file_path: mahotas/mahotas/tests/test_surf.py
imports: import numpy
  import mahotas
  import mahotas.features.surf
  from mahotas.features import _surf
  from .utils import luispedro_jpg
  import pytest
label_desc: Use image node_id 5 for calling a global function with example usage: test_surf_guassians() without return types