code: def leaves(self, fragment_type=None):
          
          leaves = self.fragments_tree.vleaves_not_empty
          if fragment_type is None:
              return leaves
          return [l for l in leaves if l.fragment_type == fragment_type]
docs: The current list of sync map fragments
          which are (the values of) the leaves
          of the sync map tree.
  
          :rtype: list of :class:`~aeneas.syncmap.fragment.SyncMapFragment`
  
          .. versionadded:: 1.7.0