code: def test_ec_disjoint():
      for i in range(1, 4):
          e = D_TO_FUNCS[i][1]
          box1, box2, _, _ = nonintersecting_boxes((40,) * i)
          assert_almost_equal(e(box1 + box2), e(box1) + e(box2))
  
imports: from itertools import combinations
  import numpy
  import numpy.linalg
  import pytest
  from numpy.testing import assert_almost_equal, assert_array_equal
  from ..None import intvol
label_desc: Use image node_id 18 for calling a global function with example usage: test_ec_disjoint() without return types