code: function install() {
    return gulp.series(async () => {
      const demoDist = config.demoDist
      const demoPackageJsonPath = path.join(demoDist, 'package.json')
      const packageJson = _.readJson(path.resolve(__dirname, '../package.json'))
      const dependencies = packageJson.dependencies || {}
  
      await _.writeFile(demoPackageJsonPath, JSON.stringify({dependencies}, null, '\t')) // write dev demo's package.json
    }, () => {
      const demoDist = config.demoDist
      const demoPackageJsonPath = path.join(demoDist, 'package.json')
  
      return gulp.src(demoPackageJsonPath)
        .pipe(gulpInstall({production: true}))
    })
  }
docs: 安装依赖包