/**
 * Push the item in the array if the item is defined and not already in the array.
 *
 * @param array - The array in which item is to be pushed.
 * @param item - The item to push.
 * @param predicate - The predicate to see if item is already in the array.
 */
export declare function pushIfNew<T>(array: T[], item: T | undefined, predicate: (arrayItem: T) => boolean): void;
/**
 * A predicate to use as an array filter in order to remove duplicates.
 *
 * @param value - The value to test.
 * @param index - The index of the current value.
 * @param array - The array.
 * @returns True if value is unique.
 */
export declare function unique<T>(value: T, index: number, array: T[]): boolean;
/**
 * Ensure that the given parameter is an array. If not, put it in an array.
 *
 * @param value - Either an array or a single item to convert.
 * @returns The parameter in an array.
 */
export declare function ensureArray<T>(value: T | T[]): T[];