import moment from 'moment'; declare module 'moment' { interface PreciseRangeValueObject extends moment.MomentObjectOutput { firstDateWasLater: boolean; } interface Moment { preciseDiff(d2: moment.MomentInput, returnValueObject?: false): string; preciseDiff(d2: moment.MomentInput, returnValueObject: true): PreciseRangeValueObject; } function preciseDiff(d1: moment.MomentInput, d2: moment.MomentInput, returnValueObject?: false): string; function preciseDiff(d1: moment.MomentInput, d2: moment.MomentInput, returnValueObject: true): PreciseRangeValueObject; }