/**
 * MultiSet (bag) implementation for js-utilities.
 * Allows duplicate elements and keeps count of each unique value.
 *
 * - Adding a negative count decreases the count, and removes the item if the count is zero or negative.
 * - Removing with a negative count increases the count.
 * - The count for any item is always positive or the item is absent.
 */
export declare class MultiSet<T> {
    private map;
    /**
     * Add an item to the MultiSet with the given count (default 1).
     * If count is negative, decreases the count. If the final count is zero or negative, removes the item.
     * @param item The item to add.
     * @param count The number of times to add (can be negative).
     */
    add(item: T, count?: number): void;
    /**
     * Remove an item from the MultiSet with the given count (default 1).
     * If count is negative, increases the count (same as add with positive count).
     * If the final count is zero or negative, removes the item.
     * @param item The item to remove.
     * @param count The number of times to remove (can be negative).
     */
    remove(item: T, count?: number): void;
    /**
     * Get the count of a specific item in the MultiSet.
     * @param item The item to count.
     * @returns The number of times the item appears (0 if not present).
     */
    count(item: T): number;
    /**
     * Check if the MultiSet contains the given item.
     * @param item The item to check.
     * @returns True if the item is present, false otherwise.
     */
    has(item: T): boolean;
    /**
     * Get the total number of items in the MultiSet (including duplicates).
     * @returns The total count of all items.
     */
    size(): number;
    /**
     * Get the number of unique items in the MultiSet.
     * @returns The number of unique items.
     */
    uniqueSize(): number;
    /**
     * Remove all items from the MultiSet.
     */
    clear(): void;
    /**
     * Convert the MultiSet to an array, repeating each item according to its count.
     * @returns An array of all items in the MultiSet.
     */
    toArray(): T[];
    /**
     * Get an iterator over [item, count] pairs in the MultiSet.
     * @returns An iterator of [item, count] pairs.
     */
    entries(): IterableIterator<[T, number]>;
}