title: Interface function in Ethereum contract
body: <p>I was looking at the code on the Ethereum website, what does this code do? </p>
  
  <pre><code>interface tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData); }
  </code></pre>
  
  <p>Available at: <a href="https://ethereum.org/token#full-coin-code" rel="nofollow noreferrer">https://ethereum.org/token#full-coin-code</a></p>
  
  <p>Thanks! </p>