docs: def sift(data, required_items=None):
      """
      Receive a ``data`` object that will be in the form
      of a normalized structure (e.g. ``{0: {'a': 0}}``) and
      filter out keys that match the ``required_items``.
      """
      required_items = required_items or []
      new_data = {}
      for k, v in data.items():
          if v[0] in required_items:
              new_data[k] = v
              continue
          for required_item in required_items:
              key = getattr(required_item, '_object', False)
              if key:
                  if v[0] == key:
                      new_data[k] = v
  
      return re_sort(new_data)