*Optional*. An array of images to consider as cache, in order to reuse build steps from a previous build. The array elements are paths to directories generated by a get step with `save: true`. This has a similar aim of cache, but it loads the images from disk instead of pulling them from the network, so that Concourse resource caching can be used. It also allows more than one image to be specified, which is useful for multi-stage Dockerfiles. If you want to cache an image used in a `FROM` step, you should put it in `load_bases` instead.