code: function _httpGet( wpreq, callback ) {
  	checkMethodSupport( 'get', wpreq );
  	const url = wpreq.toString();
  
  	let request = _auth( agent.get( url ), wpreq._options );
  	request = _setHeaders( request, wpreq._options );
  
  	return invokeAndPromisify( request, callback, returnBody.bind( null, wpreq ) );
  }
docs: HTTP Methods: Private HTTP-verb versions ======================================== 
  @method get
  @async
  @param {WPRequest} wpreq A WPRequest query object
  @param {Function} [callback] A callback to invoke with the results of the GET request
  @returns {Promise} A promise to the results of the HTTP request