code: def test_stacked_line_interpolate():
      """Test interpolated stacked line"""
      stacked = StackedLine(interpolate="cubic")
      stacked.add("one_two", [1, 2])
      stacked.add("ten_twelve", [10, 12])
      q = stacked.render_pyquery()
      assert set([v.text for v in q("desc.value")]) == set(
          ("1", "2", "11 (+10)", "14 (+12)")
      )
  
imports: from pygal import StackedLine
label_desc: Use image node_id 4 for calling a global function with example usage: test_stacked_line_interpolate() without return types