code: def test_dimension_comparison_values_unequal(self):
      try:
          self.assertEqual(self.dimension4, self.dimension8)
      except AssertionError as e:
          self.assertEqual(
              str(e),
              "Dimension parameter 'values' mismatched: [] != ['a', 'b']",
          )
  
imports: from holoviews.core import Dimension, Dimensioned
  from holoviews.element.comparison import ComparisonTestCase
label_desc: Use image node_id 11 for calling the DimensionsComparisonTestCase obj's underlying member method code with example usage: obj.test_dimension_comparison_values_unequal() without return types