defined in <a href="https://github.com/angular/angular/tree/2.0.0-alpha.37/modules/angular2/src/http/http.ts#L180-L207">angular2/src/http/http.ts (line 180)</a>
Performs any type of http request. First argument is required, and can either be a url or
a <a href='Request-class.html'><code>Request</code></a> instance. If the first argument is a url, an optional <a href='RequestOptions-class.html'><code>RequestOptions</code></a>
object can be provided as the 2nd argument. The options object will be merged with the values
of <a href='BaseRequestOptions-class.html'><code>BaseRequestOptions</code></a> before performing the request.