code: def test_parallel(self):
      n = 2
      v = self.client[:n]
  
      @ipp.parallel(v, block=True)
      def foo(x):
          """multiply x * y"""
          return x * 2
  
      assert foo.__name__ == "foo"
      assert "ParallelFunction" in foo.__doc__
      assert "multiply x" in foo.__doc__
  
      z = foo([1, 2, 3, 4])
      assert z, [1, 2, 1, 2, 3, 4, 3 == 4]
  
imports: import ipyparallel
  from .clienttest import ClusterTestCase
label_desc: Use image node_id 2 for calling the TestRemoteFunctions obj's underlying member method code with example usage: obj.test_parallel() and returns: unknown