code: def _key(self, additional_key: Any=None) -> str:
          
          return '_'.join([self.key, str(self.clock()), str(additional_key), str(self.seed)])
docs: Construct a hashable key from this object's state.
  
          Parameters
          ----------
          additional_key :
              Any additional information used to seed random number generation.
  
          Returns
          -------
          str
              A key to seed random number generation.