title: Python for loop iterating with same variable names throws error
body: <p>I am learning Python. I came across the following abnormal result, while using Python 3.6.0 REPL.</p>
  
  <pre><code>a = [1, 2, 3]
  for a in a :
     print(a)
  </code></pre>
  
  <p>output:</p>
  
  <pre><code>1
  2
  3
  </code></pre>
  
  <p>Again.</p>
  
  <p>output:</p>
  
  <pre><code>Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  TypeError: 'int' object is not iterable
  </code></pre>
  
  <p>I could see that value of 'a'.</p>
  
  <pre><code>&gt;&gt;&gt;a
  3
  </code></pre>
  
  <p>It works other iterators like <code>i</code></p>
  
  <p>I don't know how to search for the error in google. Why did <code>a</code> change?</p>