import { NodeDefinition, NodeLike, StatelessGraphNode, StatelessNodeDefinition, StatelessNodeType } from '../../types/graph';
/**
 * An instance of the [[extend]] node.
 * See the [[extend]] documentation to find out more.
 */
export interface ExtendNode extends StatelessGraphNode<'extend', ExtendNodeProperties> {
}
/**
 * A definition of the [[extend]] node.
 * See the [[extend]] documentation to find out more.
 */
export interface ExtendNodeDefinition extends StatelessNodeDefinition<'extend', ExtendNodeProperties> {
}
export interface ExtendNodeProperties {
    nodes: Array<NodeDefinition>;
}
/**
 * The implementation of the [[extend]].
 * See the [[extend]] documentation to learn more.
 */
export declare const ExtendNodeType: StatelessNodeType<'extend', ExtendNodeProperties>;
/**
 * Creates a new instance of a [[extend]] node, which is a type of a [[NodeDefinition]] used when extending a branch
 * with additional nodes. It can be compared to `Object.assign` but for branches.
 *
 * @example **Extend an existing branch**
 * ```js
 * import muster, { extend, key, query, ref, tree, value } from '@dws/muster';
 *
 * const app = muster({
 *   user: {
 *     firstName: 'Bob',
 *     lastName: 'Roberson',
 *   },
 *   extendedUser: extend(
 *     ref('user'),
 *     tree({
 *       age: value(29),
 *     }),
 *   ),
 * });
 *
 * const user = await app.resolve(query(ref('extendedUser'), {
 *   firstName: key('firstName'),
 *   lastName: key('lastName'),
 *   age: key('age'),
 * }));
 * // user = {
 * //   firstName: 'Bob',
 * //   lastName: 'Roberson',
 * //   age: 29,
 * // }
 * ```
 * This example shows how to use the [[extend]] to add additional nodes to an existing branch.
 */
export declare function extend(...nodes: Array<NodeDefinition | NodeLike>): ExtendNodeDefinition;
export declare function isExtendNodeDefinition(value: NodeDefinition): value is ExtendNodeDefinition;