code: function (attr) {
  				if (attr.indexOf('{attribution.') === -1) {
  					return attr;
  				}
  				return attr.replace(/\{attribution.(\w*)\}/,
  					function (match, attributionName) {
  						return attributionReplacer(providers[attributionName].options.attribution);
  					}
  				);
  			}
docs: replace attribution placeholders with their values from toplevel provider attribution, recursively