How to use the @pluralsight/ps-design-system-build.postcss.transform function in @pluralsight/ps-design-system-build

;(async _ => {
  await fs.mkdir('dist')

  const src = path.join('css', 'index.css')

  postcss.transform(src, path.join('dist', 'index.css'), [
    require('postcss-import'),
    require('postcss-cssnext')({ browsers: ['Last 2 versions', 'IE >= 11'] }),
    require('cssnano')
  ])
})()

;(async _ => {
  await fs.mkdir('dist')

  const src = path.join('css', 'index.css')
  postcss.transform(src, path.join('dist', 'index.css'), [
    postcssImport,
    postcss.postcssCssVarSelectors(postcssCssVarSelectorsOptions),
    autoprefixer(autoprefixerOptions)
  ])

  postcss.transform(src, path.join('dist', 'index.module.scss'), [
    postcssImport,
    postcss.postcssCssVarSassVar(),
    autoprefixer(autoprefixerOptions)
  ])
})()