  
      def mask_is_valid(self, mask_type):
          """ Ensure the given ``mask_type`` is valid for this alignments file.
  
          Every face in the alignments file must have the given mask type to successfully
          pass the test.
  
          Parameters
          ----------
          mask_type: str
 
</s> remove         """ Ensure the given ``mask_type`` is valid for this alignments file.
 </s> add         """ Ensure the given ``mask_type`` is valid for the alignments :attr:`data`. </s> remove             The mask type to check against the current alignments
 </s> add             The mask type to check against the current alignments :attr:`data` </s> remove             retval = bool(len(self.data.get(frame, list())) > 1)
        logger.trace("'%s': %s", frame, retval)
 </s> add             retval = bool(len(self._data.get(frame_name, dict()).get("faces", [])) > 1)
        logger.trace("'%s': %s", frame_name, retval) </s> remove     """ Holds processes pertaining to the alignments file.

        folder:     folder alignments file is stored in
        filename:   Filename of alignments file. If a
                    valid extension is provided, then it will be used to
                    decide the serializer otherwise compressed pickle is used.
 </s> add     """ The alignments file is a custom serialized ``.fsa`` file that holds information for each
    frame for a video or series of images.

    Specifically, it holds a list of faces that appear in each frame. Each face contains
    information detailing their detected bounding box location within the frame, the 68 point
    facial landmarks and any masks that have been extracted.

    Additionally it can also hold video meta information (timestamp and whether a frame is a
    key frame.)

    Parameters
    ----------
    folder: str
        The folder that contains the alignments ``.fsa`` file
    filename: str, optional
        The filename of the ``.fsa`` alignments file. If not provided then the given folder will be
        checked for a default alignments file filename. Default: "alignments"
        Every face in the alignments :attr:`data` must have the given mask type to successfully
  
      def mask_is_valid(self, mask_type):
          """ Ensure the given ``mask_type`` is valid for this alignments file.
  
        Every face in the alignments :attr:`data` must have the given mask type to successfully
          pass the test.
  
          Parameters
          ----------
          mask_type: str
keep keep keep keep replace keep keep keep keep keep
 lib.alignments - Slight update (#978)

* lib.alignments update:
  - Minor structure change (faces to nested dictionary)
  - Refactor internal and external methods
  - Documentation 
lib/alignments.py