title: Ocaml keyword "in"
body: <p>Where is the difference, I do not understand the purpose of the <strong>in</strong> keyword</p>
  <pre><code>let pow x =x*x;;
  let y = 3;;
  pow 3 + y;;
  
  let pow x =x*x in 
  let b = 3 in
  pow 3 + b;;
  </code></pre>