scripts/build/cache.js/Cache/Cache
class Cache:function Cache(cacheDir, version) {
  this.cacheDir = path.resolve(cacheDir || required("cacheDir"));
  this.manifest = path.join(this.cacheDir, "manifest.json");
  this.version = version || required("version");
  this.checksums = {};
  this.files = {};
  this.updated = {
    version: this.version,
    checksums: {},
    files: {},
  };
}