/**
 * @typedef {object} Phaser.Types.Physics.Matter.MatterWalls
 * @since 3.0.0
 *
 * @property {MatterJS.BodyType} [left=null] - The left wall for the Matter World.
 * @property {MatterJS.BodyType} [right=null] - The right wall for the Matter World.
 * @property {MatterJS.BodyType} [top=null] - The top wall for the Matter World.
 * @property {MatterJS.BodyType} [bottom=null] - The bottom wall for the Matter World.
 */
