code: function merge(def, opt) {
  			var mergedOpt = {};
  			var attrname;
  			for (attrname in def) {
  				mergedOpt[attrname] = def[attrname];
  			}
  			for (attrname in opt) {
  				mergedOpt[attrname] = opt[attrname];
  			}
  			return mergedOpt;
  		}
docs: Merge options