code: def columns_dataset(self):
          
          cache = self.cache
          cache_key = 'columns_dataset'
          if cache_key not in cache:
              columns_dataset = super(CachedModelVectorBuilder, self
                                      ).columns_dataset
              cache[cache_key] = columns_dataset
              self.cache = cache
          return cache[cache_key]
docs: Implement high level cache system for columns and dataset.