How to use the opal-compiler.Builder.create function in opal-compiler

const compileExt = (name, environment, skipped) => {
  if (fs.existsSync(`lib/asciidoctor/js/${name}_ext/${environment}.rb`)) {
    const module = `asciidoctor/js/${name}_ext/${environment}`
    log.debug(module)
    // Build a new instance each time, otherwise the context is shared.
    const target = `build/${name}-ext-${environment}.js`
    if (fs.existsSync(target)) {
      skipped.push(target)
      return
    }
    const opalBuilder = OpalBuilder.create()
    opalBuilder.appendPaths('lib')
    opalBuilder.setCompilerOptions({ dynamic_require_severity: 'ignore', requirable: true })
    // For performance reason we build "asciidoctor_ext" without "asciidoctor" core.
    // As a result Ruby modules required in "asciidoctor_ext" won't be found at compile time but will be resolved at runtime.
    opalBuilder.missing_require_severity = 'ignore'
    let data = opalBuilder.build(module).toString()
    fs.writeFileSync(target, data, 'utf8')
  }
}

const compileAsciidoctorCore = (asciidoctorCoreDependency) => {
  log.task('compile core lib')
  const module = `asciidoctor/lib`
  log.debug(module)
  const target = asciidoctorCoreDependency.target
  if (fs.existsSync(target)) {
    log.info(`${target} file already exists, skipping "compile" task.\nTIP: Use "npm run clean:core" to compile again from Asciidoctor Ruby.`)
    return
  }
  const opalBuilder = OpalBuilder.create()
  opalBuilder.appendPaths('build/asciidoctor/lib')
  opalBuilder.appendPaths('node_modules/opal-compiler/src/stdlib')
  opalBuilder.appendPaths('lib')
  opalBuilder.setCompilerOptions({ dynamic_require_severity: 'ignore' })
  fs.writeFileSync(target, opalBuilder.build('asciidoctor').toString(), 'utf8')

  replaceUnsupportedFeatures(asciidoctorCoreDependency)
  applyPatches(asciidoctorCoreDependency)
}

const compileExamples = () => {
  log.task('compile examples')
  bfs.mkdirsSync(builder.examplesBuildDir)

  const opalBuilder = OpalBuilder.create()
  opalBuilder.appendPaths('build/asciidoctor/lib')
  opalBuilder.appendPaths('node_modules/opal-compiler/src/stdlib')
  opalBuilder.appendPaths('lib')

  fs.writeFileSync(path.join(builder.examplesBuildDir, 'userguide_test.js'), opalBuilder.build('examples/userguide_test.rb').toString(), 'utf8')
}