--- inject([init]) {|result, item| ... }   ruby 1.7 feature

    ǽ˽ init  self κǽǤ˥֥å
    ¹Ԥޤ2 ܰʹߤΥ롼פǤϡΥ֥åμ¹Է̤ 
    self μǤ˽缡֥å¹Ԥޤƺ
    ǤޤǷ֤ǸΥ֥åμ¹Է̤֤ޤ

    Ǥξ init ֤ޤ

     init άϡǽƬǤ 2 ܤ
    Ǥ֥åϤޤξ硢Ǥ 1 ĤʤХ֥å
    ¹Ԥ˺ǽǤ֤ޤǤʤ nil ֤
    

    : 
      פη׻
        p [1,2,3,4,5].inject(0) {|result, item| result + item }
          => 15

      ϰʲΤ褦˽񤯤ΤƱǤ
          result = 0
          [1,2,3,4,5].each {|v| result += v }
          p result
          => 15

