code: def reduce(self):
          
          support = frozenset(range(1, self.nvars+1))
          new_clauses = set()
          for clause in self.clauses:
              vs = list(support - {abs(uniqid) for uniqid in clause})
              if vs:
                  for num in range(1 << len(vs)):
                      new_part = {v if bit_on(num, i) else ~v
                                  for i, v in enumerate(vs)}
                      new_clauses.add(clause | new_part)
              else:
                  new_clauses.add(clause)
          return self.__class__(self.nvars, new_clauses)
docs: Reduce to a canonical form.