title: what is the meaning of "pragma style" in webpack?
body: <p>in the <a href="http://webpack.github.io/docs/configuration.html#devtool" rel="noreferrer">devtool configuration docs</a> they say:</p>
  
  <blockquote>
    <p>Prefixing @, # or #@ will enforce a pragma style. (Defaults to #,
    recommended)</p>
  </blockquote>
  
  <p>what it the meaning of that?</p>