import { Request } from "https://deno.land/x/doa@v1.0.0/request.ts";
Return request header. If the header is not set, will return an empty string.
The Referrer header field is special-cased, both Referrer and
Referer are interchangeable.
Examples:
this.get('Content-Type');
// => "text/plain"
this.get('content-type');
// => "text/plain"
this.get('Something');
// => ''