Return all unique combinations (up to permutation) of n elements,
        taken without replacement from the contents of the jagged dimension.
        Combinations are ordered such that those of the first elements precede later ones,
        e.g. for n=2: (0,1), (0,2), (1,2), (0,3), (1,3), (2,3), (0,4), ...

def choose(self, n):
        """
        Return all unique combinations (up to permutation) of n elements,
        taken without replacement from the contents of the jagged dimension.
        Combinations are ordered such that those of the first elements precede later ones,
        e.g. for n=2: (0,1), (0,2), (1,2), (0,3), (1,3), (2,3), (0,4), ...
        """
        args = self._argchoose(n, absolute=True)
        columns = (self.content[args.content[c]] for c in args.columns)
        out = self.JaggedArray.fromoffsets(args.offsets, self.Table.named("tuple", *columns).flattentuple())
        return out