def _initialize_clauses(self, clauses):
        self.clauses = []
        for cls in clauses:
            self.clauses.append(list(cls))

        for i in range(len(self.clauses)):

            # Handle the unit clauses
            if 1 == len(self.clauses[i]):
                self._unit_prop_queue.append(self.clauses[i][0])
                continue

            self.sentinels[self.clauses[i][0]].add(i)
            self.sentinels[self.clauses[i][-1]].add(i)

            for lit in self.clauses[i]:
                self.occurrence_count[lit] += 1
Set up the clause data structures needed.
dataset/ETHPy150Open sympy/sympy/sympy/logic/algorithms/dpll2.py/SATSolver._initialize_clauses