Const sources
sources: Record<pkg.PackageName, Record<pkg.RelativePath, pkg.Source>> = Object.assign({},...Object.entries(packages).map( ([ packageName, { sources } ]) => ({[packageName]: Object.assign({},...Object.entries(sources).map(([ relativePath, source ]:[ pkg.RelativePath, string | pkg.ContentURI ]) => ({[relativePath]: (typeof source === "string")? source: exampleSource(packageName, relativePath)})))})))