def _compute_existing(self, request, biiout):
        result = []
        for block_version, deps in request.existing.iteritems():
            if request.update or request.downgrade or request.modify:
                hypothesis = self._compute_modify(block_version, deps, request, biiout)
            else:
                hypothesis = []
            hypothesis.append(Hypothesis(block_version, request.existing[block_version],
                                         self.translator, request.block_names, biiout))
            result.append(hypothesis)
        return result
return a list of list of hypothesis for already defined (existing)
dataset/ETHPy150Open biicode/bii-server/find/finder_service.py/FindService._compute_existing