Added the optional parameter to the save function.
Added the optional parameter to the save function.

dsebastien/DefinitelyTyped,georgemarshall/DefinitelyTyped,borisyankov/DefinitelyTyped,markogresak/DefinitelyTyped,dsebastien/DefinitelyTyped,mcliment/DefinitelyTyped,georgemarshall/DefinitelyTyped,georgemarshall/DefinitelyTyped,georgemarshall/DefinitelyTyped,borisyankov/DefinitelyTyped