code: def is_possible(self) -> bool:
          
          if self._is_possible is not None:
              return self._is_possible
          solver = Solver()
          solver.set_timeout(self._default_timeout)
          for constraint in self[:]:
              constraint = (
                  symbol_factory.Bool(constraint)
                  if isinstance(constraint, bool)
                  else constraint
              )
              solver.add(constraint)
          self._is_possible = solver.check() != unsat
          return self._is_possible
docs: :return: True/False based on the existence of solution of constraints