code: function( queryOptions, callback ) {
  		var url = this.getMapUrl( this.baseUrl, queryOptions );
  		debug( 'Fetching %s', url );
  		var stream = request.get( url );
  		stream.end( function( err, res ) {
  			if ( err ) {
  				debug( 'Error requesting getMap to server: %j', err );
  				return callback( err );
  			}
  			if ( !res.ok ) {
  				debug( 'WMS error response %s', res.text );
  				err = new Error( res.text );
  				return callback( err );
  			}
  			if ( typeof callback === 'function' ) {
  				callback( err, res.body );
  			}
  		} );
  		return stream;
  	}
docs: Gets an image for a layer from a WMS service
  
  @param {Object} [Optional] queryOptions. Options passed as GET parameters
  @param {Function} callback.
  - {Error} null if nothing bad happened
  - {Buffer} WMS GetMap response as a buffer. It usually is a PNG/JPEG/GIF image
  @returns {Stream} you can use it to pipe to a file.
  If you pipe the stream, the parameter `callback` will be ignored