export declare class MarkupAttributes {
    private attributes;
    set(key: string, value: string): MarkupAttributes;
    delete(key: string): MarkupAttributes;
    stringify(): string;
    /** Returns a copy of this object. */
    copy(): MarkupAttributes;
    /**
     * Assigns the attributes of the given `MarkupAttributes` to this
     * object.
     */
    assign(other: MarkupAttributes): MarkupAttributes;
    /**
     * Returns a new `MarkupAttributes` object that is a merge of `this`
     * object and the given `MarkupAttributes`.
     *
     * The given `MarkupAttributes` will take precedence over `this`
     * object.
     */
    merge(other: MarkupAttributes): MarkupAttributes;
}