Override default flow definition

flow-override.js

// @flow

declare class Date {
    constructor(): void;
    constructor(timestamp: number): void;
    constructor(dateString: string): void;
    constructor(year: number, month: number, day?: number, hour?: number, minute?: number, second?: number, millisecond?: number): void;
    getDate(): number;
    getDay(): number;
    getYear(): number;
    getFullYear(): number;
    getHours(): number;
    getMilliseconds(): number;
    getMinutes(): number;
    getMonth(): number;
    getSeconds(): number;
    getTime(): number;
    getTimezoneOffset(): number;
    getUTCDate(): number;
    getUTCDay(): number;
    getUTCFullYear(): number;
    getUTCHours(): number;
    getUTCMilliseconds(): number;
    getUTCMinutes(): number;
    getUTCMonth(): number;
    getUTCSeconds(): number;
    setDate(date: number): number;
    setFullYear(year: number, month?: number, date?: number): number;
    setHours(hours: number, min?: number, sec?: number, ms?: number): number;
    setMilliseconds(ms: number): number;
    setMinutes(min: number, sec?: number, ms?: number): number;
    setMonth(month: number, date?: number): number;
    setSeconds(sec: number, ms?: number): number;
    setTime(time: number): number;
    setUTCDate(date: number): number;
    setUTCFullYear(year: number, month?: number, date?: number): number;
    setUTCHours(hours: number, min?: number, sec?: number, ms?: number): number;
    setUTCMilliseconds(ms: number): number;
    setUTCMinutes(min: number, sec?: number, ms?: number): number;
    setUTCMonth(month: number, date?: number): number;
    setUTCSeconds(sec: number, ms?: number): number;
    toDateString(): string;
    toISOString(): string;
    toJSON(key?: any): string;
    toLocaleDateString(locales?: string, options?: Date$LocaleOptions): string;
    toLocaleString(locales?: string, options?: Date$LocaleOptions): string;
    toLocaleTimeString(locales?: string, options?: Date$LocaleOptions): string;
    toTimeString(): string;
    toUTCString(): string;
    valueOf(): number;

    static ():string;
    static now(): number;
    static parse(s: string): number;
    static UTC(year: number, month: number, date?: number, hours?: number, minutes?: number, seconds?: number, ms?: number): number;
    // multiple indexers not yet supported
    [key: $SymbolToPrimitive]: (hint: 'string' | 'default' | 'number') => string | number;
}

const myDate = new Date();
const shortYear = myDate.getYear();