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                <div id="app" />




                const languages = [

// one liner
const Language = ({language}) => <li>{language}</li>

Language.propTypes = {
  message: React.PropTypes.string.isRequired

* If there are more than one line.
* Please notice that curly brackets are optional here,
* however I uses them for readability
const LanguagesList = ({languages}) => (
    { => <Language language={language} />)}

LanguagesList.PropTypes = {
  languages: React.PropTypes.array.isRequired

* This syntax is used if there are more work is besided just JSX presentation
* For instance some data manipulations needs to be done.
* Please notice that curly brackets after return are required,
* Otherwise return will return nothing (undefined)
const LanguageSection = ({header, languages}) => {
  // do some work
  const formattedLanguages = => language.toUpperCase())
  return (
      <LanguagesList languages={formattedLanguages} />

LanguageSection.PropTypes = {
  header: React.PropTypes.string.isRequired,
  languages: React.PropTypes.array.isRequired

    languages={languages} />,