配列とハッシュはお互いにネスト可能
names:
- Hanako
- Sumire
- Momoko
emails:
- hanako@mail.com
- sumire@mail.net
- momoko@mail.org
⇒ array( 'names' => array( 'Hanako', 'Sumire', 'Momoko' ), 'emails' => array( 'hanako@mail.com', 'sumire@mail.net', 'momoko@mail.org' ) )