title: Double quotes inside single quotes inside an re expression (python)
body: <p>I am new to python. I was going through a repository on gitHub , and I saw the following line of code to extract all URLs from a webpage. I understand Regular expressions and capture groups , but I don't understand why there are extra double quotation marks enclosed within the single quotation marks? </p>
  
  <pre><code>links = re.findall('"((http|ftp)s?://.*?)"', html)
  </code></pre>
  
  <p>That is, how is it different from the following code ?</p>
  
  <pre><code>links = re.findall('((http|ftp)s?://.*?)', html)
  </code></pre>
  
  <p>I tried experimenting and saw that only the first one matches the URL syntax correctly but the second one doesn't . But I don't understand why.</p>
  
  <p>Any help is appreciated.</p>
  
  <p>Thank you.</p>