docs: def use(self, kind, name):
          """
          Mark a node name as used.
          """
          try:
              params = self._parse(name)
              index = int(params['index'], 10)
              if index in self._free[kind]:
                  self._free[kind].remove(index)
              top = self._top[kind]
              if index > top:
                  self._free[kind].update(range(top + 1, index))
                  self._top[kind] = index
          except ValueError:
              log.warning(
                  "Cannot extract numerical index"
                  " from node name `%s`!", name)