title: Solidity setting a mapping to empty
body: <p>I am trying to create a smart contract using Solidity 0.4.4.</p>
  <p>I was wondering if there is a way to set a mapping with some values already entered to an empty one?</p>
  <p>For example:</p>
  <p>This initailises a new mappping</p>
  <p><code>mapping (uint =&gt; uint) map;</code></p>
  <p>Here I add some values</p>
  <p><code>map[0] = 1;</code></p>
  <p><code>map[1] = 2;</code></p>
  <p>How can I set the map back to empty without iterating through all the keys?</p>
  <p><strong>I have tried delete but my contract does not compile</strong></p>