ts: Minor fixes to optional arg types

index.d.ts

@@ -222,7 +222,7 @@ export class Document extends AST.Collection {
   /** Set `handle` as a shorthand string for the `prefix` tag namespace. */
   setTagPrefix(handle: string, prefix: string): void
   /** A plain JavaScript representation of the document `contents`. */
-  toJSON(arg: any): any
+  toJSON(arg?: any): any
   /** A YAML representation of the document. */
   toString(): string
 }

types.d.ts

@@ -24,15 +24,15 @@ export class Schema {
    * Convert any value into a `Node` using this schema, recursively turning
    * objects into collectsions.
    *
-   * @param wrapScalars If undefined or `true`, also wraps plain values in
-   *   `Scalar` objects; if `false` and `value` is not an object, it will be
-   *   returned directly.
+   * @param wrapScalars If `true`, also wraps plain values in `Scalar` objects;
+   *   if undefined or `false` and `value` is not an object, it will be returned
+   *   directly.
    * @param tag Use to specify the collection type, e.g. `"!!omap"`. Note that
    *   this requires the corresponding tag to be available in this schema.
    */
   createNode(
     value: any,
-    wrapScalars: boolean,
+    wrapScalars?: boolean,
     tag?: string,
     ctx?: Schema.CreateNodeContext
   ): AST.Node