1. The second argument of getOption should be marked as optional per
jsdoc at: http://dygraphs.com/jsdoc/symbols/Dygraph.html#getOption
2. 'boolean' is typo'd as 'Boolean' in updateOptions.
/** @type {function(): string} */
Dygraph.prototype.toString;
/** @type {function(): string} */
Dygraph.prototype.toString;
-/** @type {function(string, string)} */
+/** @type {function(string, string=)} */
Dygraph.prototype.getOption;
/** @type {function(): number} */
Dygraph.prototype.getOption;
/** @type {function(): number} */
/** @type {function(): number} */
Dygraph.prototype.numAxes;
/** @type {function(): number} */
Dygraph.prototype.numAxes;
-/** @type {function(Object, Boolean=)} */
+/** @type {function(Object, boolean=)} */
Dygraph.prototype.updateOptions;
/** @type {function(number, number)} */
Dygraph.prototype.updateOptions;
/** @type {function(number, number)} */