import Sequence from "./Sequence";
export declare class Count {
    /**
     * Returns the number of elements of this sequence. If `predicate` is present, returns
     * the number of elements matching the given `predicate`.
     *
     * @param {(T) => boolean} predicate
     * @returns {number}
     */
    count<T>(this: Sequence<T>, predicate?: (item: T) => boolean): number;
}