/**
 * Transforms a string to a BigInt (getter).
 *
 * @param this - The object containing the property to transform
 * @param propName - The name of the property to transform
 * @returns A function that transforms the string property into a BigInt
 */
export declare function stringToBigIntTransform<T extends {
    [k in K]?: string | null | undefined;
}, K extends keyof T>(propName: K): (this: T) => bigint | Extract<T[K], undefined | null>;