title: How to flash message with variables in Flask
body: <p>I want to flash a message with a variable in flask. Can anyone tell me how can i do so.
  For example:</p>
  <pre class="lang-py prettyprint-override"><code>a = 3
  flash(&quot;message + A + message continues&quot;)
  </code></pre>
  <p>I want to achieve this.</p>