code: def satisfy_one(self, assumptions=None, **params):
          
          verbosity = params.get('verbosity', 0)
          default_phase = params.get('default_phase', 2)
          propagation_limit = params.get('propagation_limit', -1)
          decision_limit = params.get('decision_limit', -1)
          seed = params.get('seed', 1)
          return picosat.satisfy_one(self.nvars, self.clauses, assumptions,
                                     verbosity, default_phase, propagation_limit,
                                     decision_limit, seed)
docs: If the input CNF is satisfiable, return a satisfying input point.
          A contradiction will return None.