code: def test_basic_cache():
      t = DummyModel()
      s = Sphere(theta=[0], phi=[0])
  
      assert_(t.cache_get("design_matrix", s) is None)
  
      m = [[1, 0], [0, 1]]
  
      t.cache_set("design_matrix", key=s, value=m)
      assert_equal(t.cache_get("design_matrix", s), m)
  
      t.cache_clear()
      assert_(t.cache_get("design_matrix", s) is None)
  
imports: from dipy.reconst.cache import Cache
  from dipy.core.sphere import Sphere
  from numpy.testing import assert_, assert_equal
label_desc: Use image node_id 1 for calling a global function with example usage: test_basic_cache() without return types