code: def getReffs(self, level=1, subreference=None):
          
          if self.depth is not None:
              level += self.depth
  
          return self.getValidReff(level, subreference)
docs: Reference available at a given level
  
          :param level: Depth required. If not set, should retrieve first encountered level (1 based)
          :type level: Int
          :param subreference: Subreference (optional)
          :type subreference: CtsReference
          :rtype: [text_type]
          :returns: List of levels