import { Operator } from '../Seq';
/**
 * Returns a sequence in which the current sequence and the specified sequence are concatenated.
 *
 * ```typescript
 * const result = from([1, 2]).pipe(concat([3,4])).toArray();
 * //result: [1,2,3,4]
 * ```
 *
 * @param target Sequence to be concatenated.
 * @returns Operator function.
 * @typeParam T Source element type.
 * @category Operators
 */
export declare const concat: <T>(target: Iterable<T>) => Operator<T, T>;