title: Escape single quote (') in raw string r'...'
body: <p>I want it to print out</p>
  
  <pre><code>this is '(single quote) and "(double quote)
  </code></pre>
  
  <p>I use the following (I want to use raw string 'r' here)</p>
  
  <pre><code>a=r'this is \'(single quote) and "(double quote)' 
  </code></pre>
  
  <p>but it prints out</p>
  
  <pre><code>this is \'(single quote) and "(double quote)
  </code></pre>
  
  <p>What is the correct way to escape ' in raw string?</p>