code: def mock_lockfile_update(path):
      
      updated_lockfile_contents = {
          'package1': '1.2.0'
      }
      with open(path, 'w+') as f:
          f.write(json.dumps(updated_lockfile_contents, indent=4))
      return updated_lockfile_contents
docs: This is a mock update. In place of this, you might simply shell out
      to a command like `yarn upgrade`.