code: def inner(self):
      [x, y, z] = self.foreach_stack()
  
      # assert that lengths are correct
      assert_equals(len(self.x), x[1])
      assert_equals(len(self.y), y[1])
      # Note: We can't assert the actual num_splits for unbounded-foreach.
      assert_equals(None, z[1])  # expected=len(self.z) for bounded.
  
      # assert that variables are correct given their indices
      assert_equals(x[2], self.x[x[0]])
      assert_equals(y[2], self.y[y[0]])
      assert_equals(z[2], self.z[z[0]])
  
      assert_equals(self.input, z[2])
      self.combo = x[2] + y[2] + z[2]
  
imports: from metaflow_test import MetaflowTest, ExpectationFailed, steps, tag
label_desc: Use image node_id 2 for calling the NestedUnboundedForeachTest obj's underlying member method code with example usage: obj.inner() without return types