docs: def _get_val2_dict_from_diff_dict(diff_dict):
      '''
      Returns a dictionaries with the values stored in val2 of a diff dict.
      '''
      ret_dict = {}
      for p in diff_dict.keys():
          if not isinstance(diff_dict[p], dict):
              raise ValueError('Unexpected diff difct \'{0}\''.format(diff_dict))
          if 'val2' in diff_dict[p].keys():
              ret_dict.update({p: diff_dict[p]['val2']})
          else:
              ret_dict.update(
                  {p: _get_val2_dict_from_diff_dict(diff_dict[p])})
      return ret_dict