--- function#timeout(sec) {|i| .... }
--- function#timeout(sec, exception_class) {|i| .... }  ruby 1.7 feature
    ֥å sec äδդǼ¹Ԥޤ
    ֥åμ¹Ի֤¤᤮Ȥ㳰
    TimeoutError ȯޤ
    exception_class ꤷˤ TimeoutError 
    㳰ȯޤ

    ޤ sec  nil ΤȤ»֤ʤ
    ֥å¹Ԥޤ

    : 

      timeout ˤߤ Thread ˤäƼ¸ƤޤC 
      ٥Ǽ졢Ruby ΥåɤʤФ 
      timeout ̵ϤǤν Ruby Ǽʤ C ¦ Ruby 
      ΥåɤռƤɬפޤ
      timeout [trap::timeout]⻲

