import { OperatorFunction } from 'rxjs';
/**
 * Creates an operator function that filters an Observable stream, emitting only those items from the source Observable
 * that have a specified property, optionally checking if the property's value matches a given value.
 *
 * @template T The type of the items emitted by the source Observable, which must be an object, or null, or undefined.
 * @template V The type of the object specifying the property to check for in the items emitted by the source Observable.
 * @param propertyKey The property key to check for in the emitted items. This key must exist in type V.
 * @param value Optional. The value to compare against the property's value. If provided, only items where the property's
 * value matches this argument will be emitted.
 * @returns An OperatorFunction that takes a source Observable of type T and returns an Observable of type T & V,
 * emitting only items that have the specified property, and if a value is provided, where the property's value
 * matches the provided value.
 *
 * ### Example
 * ```typescript
 * // Assuming an Observable of objects with type {id: number, name: string}
 * const source$ = of({id: 1, name: 'Alice'}, {id: 2, name: 'Bob'});
 * const filtered$ = source$.pipe(hasProperty<'name'>('name'));
 * // filtered$ will emit both objects as they both have the 'name' property.
 * ```
 *
 * ### Note
 * - The function uses the `HasPropertyOperator` class internally to perform the filtering.
 * - If `value` is provided, strict equality (===) is used for comparison.
 *
 */
export declare function hasProperty<T extends object | null | undefined, V>(propertyKey: keyof V, value?: any): OperatorFunction<T, T & V>;