title: OCaml Optional Argument
body: <p>How can I write a function in OCaml in which one or more argument are optional?</p>
  
  <pre><code>let foo x y z = if(x+y &gt; z) then true else false;;
  </code></pre>
  
  <p>If foo do not receive the <code>z</code> argument it uses <code>0</code> as <code>z</code>.</p>
  
  <pre><code>foo 3 3 2 -&gt; true
  foo 3 3 10 -&gt; false
  foo 2 1 -&gt; true
  </code></pre>
  
  <p>Is there any OCaml feature to achieve this?</p>