/**
 * Adds `faceUp` property and `flip*()` methods.
 * The entity now has two sides. Like a card or coin.
 * @category Trait
 */
export declare class TwoSidedTrait {
    /**
     * @category TwoSidedTrait
     */
    faceUp: boolean;
    /**
     * Flip the entity on to the other side
     * @category TwoSidedTrait
     */
    flip(): void;
    /**
     * Flip the entity to reveal its face
     * @category TwoSidedTrait
     */
    flipUp(): void;
    /**
     * Flip the entity to reveal its back side
     * @category TwoSidedTrait
     */
    flipDown(): void;
}