import { IterableX } from '../iterable';
/**
 * Filters a sequence of values based on a predicate.
 * @param {Iterable<T>} source Source sequence.
 * @param {function(value: T, index: number): boolean} predicate A function to test each source element for a condition.
 * @param {Object} [thisArg] Value to use as this when executing callback.
 * @return {Iterable<T>} Sequence that contains elements from the input sequence that satisfy the condition.
 */
export declare function filter<T>(source: Iterable<T>, predicate: (value: T, index: number) => boolean, thisArg?: any): IterableX<T>;