/**
 * Represents a size range with a lower and an optional upper bound.
 *
 * This is used as hints in response bodies to determine their possible size.
 */
export declare class SizeHint {
    readonly lower: number;
    readonly upper: number | null;
    private constructor();
    /**
     * Creates a size hint with an unknown size.
     */
    static unbounded(): SizeHint;
    /**
     * Creates a size hint with a known range.
     */
    static range(lower: number, upper: number): SizeHint;
    /**
     * Creates a size hint with an exact size.
     */
    static exact(value: number): SizeHint;
    /**
     * Returns an exact size if both `lower` and `upper` are equal.
     */
    exact(): number | null;
}