code: function respond(status, headers, body) {
      this._setResponseHeaders(headers || {});
      this.status = typeof status == "number" ? status : 200;
      this.statusText = httpStatusCodes[this.status];
      this._setResponseBody(body || "");
    }
docs: /*
  Forces a response on to the FakeXMLHttpRequest object.
  
  This is the public API for faking responses. This function
  takes a number status, headers object, and string body:
  
  ```
  xhr.respond(404, {Content-Type: 'text/plain'}, "Sorry. This object was not found.")
  
  ```