Mark a node name as used.

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)