title: Python Regex to match optionally double-quoted string
body: <p>I want to match an optionally double-quoted string with regular expression using Python regex module <em>re</em></p>
  
  <p>The expression should give the following results: </p>
  
  <p><code>"Assets".</code> => Should Match</p>
  
  <p><code>Assets.</code>   => Should Match</p>
  
  <p><code>"Assets.</code>  => Shouldn't Match</p>
  
  <p><code>Assets".</code>  => Shouldn't Match</p>
  
  <p>I tried to achieve this using back reference in regular expression : </p>
  
  <pre><code>("?)Assets\1 
  </code></pre>
  
  <p>However, it matches even if there is no matching end quote.
  <code>"Assets.</code> -> neglects initial quote ", and matches the rest of the word.</p>
  
  <p>What would be right expression for this ?</p>