code: function createFlow() {
    fs.writeFileSync(
      path.join(process.cwd(), pkg.main + '.flow'),
      createFlowFile(),
      'utf-8',
    )
    fs.writeFileSync(
      path.join(process.cwd(), pkg.module + '.flow'),
      createFlowFile(),
      'utf-8',
    )
  }
docs: Create a flow file that references the original source file, so Flow mapping is kept intact.
  https://blog.kentcdodds.com/distributing-flow-type-definitions-for-node-and-browser-modules-3952ad38b357