export declare function once<T extends Function>(this: any, fn: T): T;
export declare function removeObjectFromArray<T = any>(array: Array<T>, object: T, comparator?: (o1: T, o2: T) => boolean): void;
export declare function diffSets<T>(before: Set<T>, after: Set<T>): {
    removed: T[];
    added: T[];
};
export declare function findFirstTruthy<T>(...sources: Array<T | (() => T)>): T | undefined;
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