code: def has_adjacent_leaves_only(self):
          
          leaves = self.leaves()
          for i in range(len(leaves) - 1):
              current_interval = leaves[i].interval
              next_interval = leaves[i + 1].interval
              if not current_interval.is_adjacent_before(next_interval):
                  return False
          return True
docs: Return ``True`` if the sync map fragments
          which are the leaves of the sync map tree
          are all adjacent.
  
          :rtype: bool
  
          .. versionadded:: 1.7.0