How to use the pegjs.util.clone function in pegjs

it( "shallow clones an object", function () {

            expect( util.clone( meta ) )
                .to.be.an( "object" )
                .that.has.own.includes( meta );

        } );

function commented( grammar, comments, options ) {

        function toObject( result, comment ) {

            result[ comment.offset ] = {
                text: comment.text,
                multiline: comment.multiline,
            };

            return result;

        }

        grammar = util.clone( grammar );
        grammar.comments = options.extractComments ? comments.reduce( toObject, {} ) : null;
        return grammar;

    }