/** @module array/appendUnique.ts */
import { AppendUnique as AppendUnique_, BasicTypes } from '../helper-types';
interface IAppendUniqueSecondLayer<N1 extends any[]> {
    <Item extends BasicTypes, A extends BasicTypes, B extends [A, ...A[]], C extends [B, ...B[]], D extends [C, ...C[]], E extends [D, ...D[]], F extends [E, ...E[]], G extends [F, ...F[]], H extends [G, ...G[]], I extends [H, ...H[]], J extends [I, ...I[]], K extends [J, ...J[]], L extends [K, ...K[]], M extends [L, ...L[]], N extends [M, ...M[]], O extends [N, ...N[]], P extends [O, ...O[]], Q extends [P, ...P[]], N2 extends [(A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P), ...Array<A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P>]>(item: N2): AppendUnique_<N1, N2>;
    <Item extends BasicTypes>(item: Item): AppendUnique_<N1, Item>;
}
interface AppendUnique {
    <_A extends BasicTypes, _B extends [_A, ..._A[]], _C extends [_B, ..._B[]], _D extends [_C, ..._C[]], _E extends [_D, ..._D[]], _F extends [_E, ..._E[]], _Narrow extends [(_A | _B | _C | _D | _E | _F), ...Array<_A | _B | _C | _D | _E | _F>], A extends BasicTypes, B extends [A, ...A[]], C extends [B, ...B[]], D extends [C, ...C[]], E extends [D, ...D[]], F extends [E, ...E[]], G extends [F, ...F[]], H extends [G, ...G[]], I extends [H, ...H[]], J extends [I, ...I[]], K extends [J, ...J[]], L extends [K, ...K[]], M extends [L, ...L[]], N extends [M, ...M[]], O extends [N, ...N[]], P extends [O, ...O[]], Q extends [P, ...P[]], Narrow extends [(A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P), ...Array<A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P>]>(arr: Narrow, item: _Narrow): AppendUnique_<Narrow, _Narrow>;
    <Item extends BasicTypes, A extends BasicTypes, B extends [A, ...A[]], C extends [B, ...B[]], D extends [C, ...C[]], E extends [D, ...D[]], F extends [E, ...E[]], G extends [F, ...F[]], H extends [G, ...G[]], I extends [H, ...H[]], J extends [I, ...I[]], K extends [J, ...J[]], L extends [K, ...K[]], M extends [L, ...L[]], N extends [M, ...M[]], O extends [N, ...N[]], P extends [O, ...O[]], Q extends [P, ...P[]], Narrow extends [(A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P), ...Array<A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P>]>(arr: Narrow, item: Item): AppendUnique_<Narrow, Item>;
    <A extends BasicTypes, B extends [A, ...A[]], C extends [B, ...B[]], D extends [C, ...C[]], E extends [D, ...D[]], F extends [E, ...E[]], G extends [F, ...F[]], H extends [G, ...G[]], I extends [H, ...H[]], J extends [I, ...I[]], K extends [J, ...J[]], L extends [K, ...K[]], M extends [L, ...L[]], N extends [M, ...M[]], O extends [N, ...N[]], P extends [O, ...O[]], Q extends [P, ...P[]], Narrow extends [(A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P), ...Array<A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P>]>(arr: Narrow): IAppendUniqueSecondLayer<Narrow>;
    <A, B>(arr: A[], item: B): Array<A | B>;
    <A, B>(arr: A[]): (item: B) => Array<A | B>;
}
/**
 * Appends an item to an array if the item isn't already in array. Attempts literal types if possible.
 * @param arr Array to append to
 * @param item Item to append if not already in array
 * @sig a[] -> a -> a[]
 * @example
 * appendUnique([1,2,3,[4]], [4])
 * //=> [1,2,3,[4]] : [1,2,3,[4]]
 */
export declare const appendUnique: AppendUnique;
export default appendUnique;