gistfile1.txt

$ http localhost:5000/trope Accept:application/json
HTTP/1.0 200 OK
Content-Length: 130
Content-Type: application/json
Date: Wed, 19 Feb 2014 14:11:31 GMT
Server: HTTP::Server::PSGI
Vary: Accept

{
    "items": [
        {
            "content": "test", 
            "id": 1, 
            "summary": "test", 
            "title": "test"
        }, 
        {
            "content": "test2", 
            "id": 2, 
            "summary": "test2", 
            "title": "test2"
        }
    ]
}

gistfile2.txt

$ http localhost:5000/trope Accept:text/html
HTTP/1.0 200 OK
Content-Length: 27
Content-Type: text/html
Date: Wed, 19 Feb 2014 14:12:15 GMT
Server: HTTP::Server::PSGI
Vary: Accept

<h1>test</h1><h1>test2</h1>