def _match_rhs(self, rhs, span, constituents):
        (start, end) = span

        # Base case
        if start >= end and rhs == (): return [[]]
        if start >= end or rhs == (): return []

        # Find everything that matches the 1st symbol of the RHS
        childlists = []
        for split in range(start, end+1):
            l=constituents.get((start,split,rhs[0]))
            if l is not None:
                rights = self._match_rhs(rhs[1:], (split,end), constituents)
                childlists += [[l]+r for r in rights]

        return childlists
Return the build number of the Linux distribution.
dataset/ETHPy150Open nltk/nltk/nltk/parse/viterbi.py/ViterbiParser._match_rhs--crossover with--dataset/ETHPy150Open nir0s/distro/distro.py/LinuxDistribution.build_number