code: function(futures) {
  		this.resolve(function(err) {
  			if (!err) {
  				return;
  			}
  			if (futures instanceof Array) {
  				for (var ii = 0; ii < futures.length; ++ii) {
  					futures[ii].throw(err);
  				}
  			} else {
  				futures.throw(err);
  			}
  		});
  		return this;
  	}
docs: Propogate only errors to an another future or array of futures.