title: Status code for a response that work's but doesn't have a answer
body: <p>I'm current building a API that can return a determinated city based on it name. My code it's working, the problem that i'm facing is the correct status code to use on a request, that fulfilled itself, but doesn't has a answer, because the city wasn't found.</p>
  <p>Which status code should i use in this case? I tried use <code>204 NO-CONTENT</code>, but then the response doesn't have a body and my custom exception for city-not-found became useless.</p>