title: Strange Effect of Python Assignment?
body: <p>As we all know, for Python, we could easily assignment multiple variables in one line. But here I encounter a strange situation. Say we have a list: </p>
  
  <pre><code>x = [1, 2, 3, 4]
  </code></pre>
  
  <p>And then, we do</p>
  
  <pre><code>x[0], x[x[0]] = 2, 1
  </code></pre>
  
  <p>Finally, we would get</p>
  
  <pre><code>x = [2, 2, 3, 4]
  </code></pre>
  
  <p>instead of</p>
  
  <pre><code>x = [2, 1, 3, 4]
  </code></pre>
  
  <p>Could anyone explain what is going wrong here? How would python implement the multiple variables assignment in one line?</p>
  
  <p>Thanks in advance.</p>