title: How can I have multiple responses from a single endpoint with different parameters?
body: <p>We are looking at using the API Blueprint.  There are cases where we would like one request to return a proper response and another request to return an 'error' response such as a <code>400 bad request</code> so that other developers can work against the mock API on apiary.io with both types of responses and handle it in their applications.</p>
  
  <p>I've created a completely arbitrary example below, </p>
  
  <pre><code>## Thing [/thing/{id}]
  Gets a thing but the thing id must be a prime number!
  
  
  + Parameters
      + id (string) ... ID of the thing, a prime number!
  
  + Model (application/json)
  
      The thing itself.
  
      + Body
  
              {
                  "description": "It is green"
              }
  
  ### Retrieve a Single Gist [GET]
  + Response 200
  
      [Gist][]
  </code></pre>
  
  <p>Now somehow I would like to add in a response for <code>/thing/40</code></p>
  
  <pre><code>+ Response 400
      {  "error" : "Invalid request" }
  </code></pre>
  
  <p>But I am not sure how I would do this with the API Blueprint.  This was achievable under the 'old' style on apiary.io but we'd like to move on to the new syntax</p>