code: def test_zoom_ratio():
      f = np.zeros((128, 128))
      f[32:64, 32:64] = 128
      for z in [0.7, 0.5, 0.2, 0.1]:
          output = interpolate.zoom(f, z)
          ratio = output.sum() / f.sum()
          assert np.abs(ratio - z * z) < 0.1
  
file_path: mahotas/mahotas/tests/test_interpolate.py
imports: from mahotas import interpolate
  import numpy
  import pytest
  from pytest import raises
label_desc: Use image node_id 3 for calling a global function with example usage: test_zoom_ratio() without return types