--- push(obj1[, obj2 ...])
--- push([obj1[, obj2 ...]])    ruby 1.8 feature

    obj1, obj2 ... ֤ɲäޤ

    pop, shift, unshift ⻲Ȥ
    

    self ֤ޤ

    :
          array = [1, 2, 3]
          array.push 4
          array.push [5, 6]
          array.push 7, 8
          p array          # => [1, 2, 3, 4, [5, 6], 7, 8]

    ruby 1.8 feature: ꤷʤв⤷ޤ

