What is the rhyme scheme of this poem?

Reading Comprehension: Read the quoted parts carefully and answer the questions.I celebrate myself, and sing myself,
And what I assume you shall assume,
For every atom belonging to me as good belongs to you.
I loafe and invite my soul,
I learn and loafe at my ease observing a spear of summer grass.
What is the rhyme scheme of this poem?
【正确答案】：

FREE VERSE

【题目解析】：惠特曼创造了“自由体诗”，没有固定的节奏和韵律。