--- catch(tag) {|tag| .... }

    ֥å¹ԤƤ֤ͤޤ֥åμ¹
    tag Ʊ̾ throw Ԥ줿
    ϡ throw ͤȤޤ

    㤨аʲΥɤ¹Ԥ some_process 
    ƤӽФ줺ޤ catch ͤ 10 ǤϤʤ 25 
    ʤޤ

      ret = catch(:exit) {
         throw :exit, 25
         some_process()
         10
      }
      p ret   #=> 25

    ͥȤ롼פ break ˤäư쵤ȴ
    뤳ȤϤǤޤ
    Τ褦ʾ硢catch  㳰 [湽¤/begin] Ѥޤ

      catch(:loop1) {
        for i in 1..2
          for j in 1..2
            throw :loop1, j
          end
        end
      }

