title: Do I need to use approve method in ERC721?
body: <p>I am practicing the smart contract and NFT looks interested to me. <br>
  <a href="https://github.com/vyperlang/vyper/blob/master/examples/tokens/ERC721.vy" rel="nofollow noreferrer">ERC721 written in Vyper</a></p>
  <p>What is the mechanic of approve in it?<br>
  What is <code>isApprovedForAll</code> does?</p>
  <p>IMO. I don't need to use approve method. I just use <code>transferFrom()</code> is enough.<br>
  Correct me if I am wrong</p>