old_contents: from layers.interpretations import InterpretationsLayer
  from unittest import TestCase
  
  class InterpretationsLayerTest(TestCase):
      def test_apply_layer(self):
          return #    @todo refactor this test to use the new format
          layer = {
                  "200-2-b": [{
                      "reference": "200-Interpretations-2-b",
                      "text": "Some contents are here"
                      }],
                  "200-2-b-ii": [{
                      "reference": "200-Interpretations-2-b-ii",
                      "text": "Inner interpretaton"
                      }, {
                      "reference": "200-Interpretations-2-b",
                      "text": "Some contents are here"
                      }]}
          il = InterpretationsLayer(layer)
  
          key, value = il.apply_layer("200-2-b")
          self.assertEqual('I-200-2-b', value)
          self.assertEqual('interpretations', key)
  
          key, value = il.apply_layer("200-2-b-ii")
          self.assertEqual('I-200-2-b-ii', value)
          self.assertEqual('interpretations', key)
  
          self.assertEqual(None, il.apply_layer("200-2-b-iii"))
  
new_contents: from layers.interpretations import InterpretationsLayer
  from mock import Mock, patch
  from unittest import TestCase
  
  class InterpretationsLayerTest(TestCase):
      @patch('layers.interpretations.api_reader')
      def test_apply_layer_extra_fields(self, api_reader):
          layer = {
              "200-2-b-3-i": [{
                  "reference": "200-Interpretations-2-(b)(3)(i)",
                  "text": "Some contents are here"
              }],
          }
          api_reader.Client.return_value.regulation.return_value = {
              'some': 'node'
          }
  
          il = InterpretationsLayer(layer, 'test-version')
          il.builder = Mock()
  
          il.apply_layer('200-2-b-3-i')
          self.assertEqual(il.builder.tree, {
              'some': 'node',
              'interp_for_markup_id': '200-2-b-3-i',
              'interp_label': '2(b)(3)(i)'
          })
  
subject: Test for the new fields