new_contents: import unittest
  
  from ..api import read_notebook
  from ..execute import _parameterize_notebook
  from . import get_notebook_path
  
  
  class TestNotebookHelpers(unittest.TestCase):
      def test_preserving_tags(self):
          # test that other tags on the parameter cell are preserved
          test_nb = read_notebook(get_notebook_path("simple_execute.ipynb"))
          test_nb.node.cells[0]['metadata']['tags'].append('some tag')
  
          _parameterize_notebook(test_nb.node, 'python3', {'msg': 'Hello'})
  
          cell_zero = test_nb.node.cells[0]
          self.assertTrue('some tag' in cell_zero.get('metadata').get('tags'))
  
          cell_one = test_nb.node.cells[1]
          self.assertTrue('some tag' in cell_one.get('metadata').get('tags'))
          self.assertTrue('parameters' in cell_one.get('metadata').get('tags'))
  
      def test_default_parameters_tag(self):
          test_nb = read_notebook(get_notebook_path("simple_execute.ipynb"))
          test_nb.node.cells[0]['metadata']['tags'].append('some tag')
  
          _parameterize_notebook(test_nb.node, 'python3', {'msg': 'Hello'})
  
          cell_zero = test_nb.node.cells[0]
          self.assertTrue('default parameters'
                          in cell_zero.get('metadata').get('tags'))
          self.assertTrue('parameters'
                          not in cell_zero.get('metadata').get('tags'))
  
subject: Add tests for tagging of parameter cells