import { EventObject } from "./types.js";
/**
 * Asserts that the given event object is of the specified type or types.
 * Throws an error if the event object is not of the specified types.
  @example

  ```ts
  // ...
  entry: ({ event }) => {
    assertEvent(event, 'doNothing');
    // event is { type: 'doNothing' }
  },
  // ...
  exit: ({ event }) => {
    assertEvent(event, 'greet');
    // event is { type: 'greet'; message: string }

    assertEvent(event, ['greet', 'notify']);
    // event is { type: 'greet'; message: string }
    // or { type: 'notify'; message: string; level: 'info' | 'error' }
  },
  ```
 */
export declare function assertEvent<TEvent extends EventObject, TAssertedType extends TEvent['type']>(event: TEvent, type: TAssertedType | TAssertedType[]): asserts event is TEvent & {
    type: TAssertedType;
};