code: def get_hash(self, keys=[]):
          
          if not len(keys):
              keys = list(self.keys())
  
          string_rep = ''
          oself = self._ordered(deepcopy(self))
          for key in keys:
              string_rep += json.dumps(oself.get(key, ''), sort_keys=True)
  
          return hashlib.sha512(string_rep.encode()).hexdigest()[:16]
docs: Return a unique hash associated with the listed keys.