GET http://localhost:8000/hello
HTTP 200
`Hello World!`

GET http://localhost:8000/hello
HTTP 200
file, data.txt;

GET http://localhost:8000/hello
HTTP 200
hex, 48656c6c6f20576f726c6421;

GET http://localhost:8000/hello
HTTP 200
base64, SGVsbG8gV29ybGQh;
