Update index.d.ts

types/js-yaml/index.d.ts

@@ -43,7 +43,7 @@ declare namespace jsyaml {
 		// specifies a schema to use.
 		schema?: any;
 		// if true, sort keys when dumping YAML. If a function, use the function to sort the keys. (default: false)
-		sortKeys?: boolean;
+		sortKeys?: boolean | ((a: any, b: any) => number);
 		// set max line width. (default: 80)
 		lineWidth?: number;
 		// if true, don't convert duplicate objects into references (default: false)