in script/build.ts [125:136]
async function writeTsTypeIndex(collection: ModeCollection) {
let output = ''
const modules = [...collection.modes.keys()]
for (const mod of modules) {
output += `import ${mod} from './${mod}'\n`
}
output += `export default { ${modules.join(', ')} }`
const dir = path.join(tsDir, collection.type)
await mkdirp(dir)
fs.writeFileSync(path.join(dir, `index.ts`), output)
}