code: def register(cls, frameset, name=None):
          
          return cls_register(cls, frameset, FrameSet, ('delay', ), name=name)
docs: Register a new FrameSet as a member/attribute of this class.
              Returns the new FrameSet.
              Arguments:
                  frameset  : An existing FrameSet, or an iterable of strings.
                  name      : New name for the FrameSet, also used as the
                              classes attribute name.
                              If the `frameset` object has not `name` attribute,
                              this argument is required. It must not be empty
                              when given.