title: how to convert csv into dict format
body: <p>I have a.csv file as below:</p>
  
  <pre><code> OLD,NEW
   AA,XX
   BB,YY
   CC,ZZ
  </code></pre>
  
  <p>I wanna convert it to dict format, 
  say dict1 = {'AA':'XX','BB':'YY','CC':'ZZ'}
  Should I use DictReader or join string?</p>