code: def test_pickle_results():
      filename = "tmp.pkl"
  
      @pickle_results("tmp.pkl")
      def foo(x):
          foo.called = True
          return x * x
  
      # cleanup if necessary
      if os.path.exists(filename):
          os.remove(filename)
  
      # initial calculation: function should be executed
      foo.called = False
      assert foo(4) == 16
      assert foo.called is True
  
      # recalculation: function should not be executed
      foo.called = False
      assert foo(4) == 16
      assert foo.called is False
  
      # recalculation with different input: function should be executed
      foo.called = False
      assert foo(5) == 25
      assert foo.called is True
  
      # cleanup
      assert os.path.exists(filename)
      os.remove(filename)
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_pickle_results() and returns: unknown