/** @type {function(): string} */
Dygraph.prototype.toString;
-/** @type {function(string, string)} */
+/** @type {function(string, string=)} */
Dygraph.prototype.getOption;
/** @type {function(): number} */
/** @type {function(): number} */
Dygraph.prototype.numAxes;
-/** @type {function(Object, Boolean=)} */
+/** @type {function(Object, boolean=)} */
Dygraph.prototype.updateOptions;
/** @type {function(number, number)} */
/** @type {function(number, boolean)} */
Dygraph.prototype.setVisibility;
-/** @type {function(Array.<Object>, boolean)} */
+/** @type {function(Array.<Object>, boolean=)} */
Dygraph.prototype.setAnnotations;
/** @type {function(): Array.<Object>} */