code: def convert(self, key, value):
          
          if key not in self._dtypes:
              self.read_types()
              if key not in self._dtypes:
                  name = utils.name(value)
                  serializer = utils.serializer(name)
                  deserializer = utils.deserializer(name)
                  self._dtypes[key] = (name, serializer, deserializer)
                  with self.db:
                      self.db.execute("replace into value_types (key, value_type) values (?, ?)", (key, name))
          return self._dtypes[key][1](value)
docs: Get the serialized value for a given key.