title: Python regex with question mark literal
body: <p>I'm using Django's URLconf, the URL I will receive is <code>/?code=authenticationcode</code>
  <br>
  I want to match the URL using <code>r'^\?code=(?P&#60;code&#62;.*)$'</code> , but it doesn't work.
  <br></p>
  
  <p>Then I found out it is the problem of '?'.
  <br>
  Becuase I tried to match <code>/aaa?aaa</code> using <code>r'aaa\?aaa'</code> <code>r'aaa\\?aaa'</code> even <code>r'aaa.*aaa'</code> , all failed, but it works when it's "+" or any other character.
  <br>
  How to match the '?', is it special?</p>