de> (defaults to <code>GET</code>), <code>header</code>, <code>body</code> attributes are recognized.
</p>
<p>
The method returns a promise object.
When <code>#join</code> method of the promise is invoked, a three-argument array containing the status code, response headers, and the body is returned.
The response body is also a promise.
Applications can choose from three ways when dealing with the body: a) call <code>#each</code> method to receive the contents, b) call <code>#join</code> to retrieve the body