code: def get_cache_key(self, section, name):
          
          if not self.instance:
              return 'dynamic_preferences_{0}_{1}_{2}'.format(self.model.__name__, section, name)
          return 'dynamic_preferences_{0}_{1}_{2}_{3}'.format(self.model.__name__, self.instance.pk, section, name, self.instance.pk)
docs: Return the cache key corresponding to a given preference