'use strict';
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var PENDING = 'pending';
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var SETTLED = 'settled';
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var FULFILLED = 'fulfilled';
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var REJECTED = 'rejected';
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var NOOP = function () {};
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var isNode = typeof global !== 'undefined' && typeof global.process !== 'undefined' && typeof global.process.emit === 'function';
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var asyncSetTimer = typeof setImmediate === 'undefined' ? setTimeout : setImmediate;
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var asyncQueue = [];
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var asyncTimer;
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function asyncFlush() {
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// run promise callbacks
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for (var i = 0; i < asyncQueue.length; i++) {
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asyncQueue[i][0](asyncQueue[i][1]);
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}
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// reset async asyncQueue
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asyncQueue = [];
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asyncTimer = false;
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}
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function asyncCall(callback, arg) {
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asyncQueue.push([callback, arg]);
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if (!asyncTimer) {
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asyncTimer = true;
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asyncSetTimer(asyncFlush, 0);
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}
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}
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function invokeResolver(resolver, promise) {
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function resolvePromise(value) {
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resolve(promise, value);
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}
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function rejectPromise(reason) {
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reject(promise, reason);
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}
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try {
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resolver(resolvePromise, rejectPromise);
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} catch (e) {
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rejectPromise(e);
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}
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}
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function invokeCallback(subscriber) {
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var owner = subscriber.owner;
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var settled = owner._state;
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var value = owner._data;
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var callback = subscriber[settled];
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var promise = subscriber.then;
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if (typeof callback === 'function') {
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settled = FULFILLED;
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try {
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value = callback(value);
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} catch (e) {
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reject(promise, e);
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}
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}
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if (!handleThenable(promise, value)) {
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if (settled === FULFILLED) {
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resolve(promise, value);
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}
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if (settled === REJECTED) {
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reject(promise, value);
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}
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}
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}
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function handleThenable(promise, value) {
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var resolved;
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try {
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if (promise === value) {
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throw new TypeError('A promises callback cannot return that same promise.');
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}
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if (value && (typeof value === 'function' || typeof value === 'object')) {
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// then should be retrieved only once
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var then = value.then;
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if (typeof then === 'function') {
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then.call(value, function (val) {
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if (!resolved) {
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resolved = true;
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if (value === val) {
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fulfill(promise, val);
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} else {
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resolve(promise, val);
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}
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}
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}, function (reason) {
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if (!resolved) {
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resolved = true;
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reject(promise, reason);
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}
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});
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return true;
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}
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}
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} catch (e) {
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if (!resolved) {
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reject(promise, e);
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}
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return true;
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}
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return false;
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}
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function resolve(promise, value) {
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if (promise === value || !handleThenable(promise, value)) {
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fulfill(promise, value);
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}
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}
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function fulfill(promise, value) {
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if (promise._state === PENDING) {
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promise._state = SETTLED;
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promise._data = value;
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asyncCall(publishFulfillment, promise);
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}
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}
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function reject(promise, reason) {
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if (promise._state === PENDING) {
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promise._state = SETTLED;
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promise._data = reason;
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asyncCall(publishRejection, promise);
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}
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}
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function publish(promise) {
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promise._then = promise._then.forEach(invokeCallback);
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}
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function publishFulfillment(promise) {
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promise._state = FULFILLED;
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publish(promise);
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}
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function publishRejection(promise) {
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promise._state = REJECTED;
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publish(promise);
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if (!promise._handled && isNode) {
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global.process.emit('unhandledRejection', promise._data, promise);
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}
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}
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function notifyRejectionHandled(promise) {
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global.process.emit('rejectionHandled', promise);
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}
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/**
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* @class
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*/
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function Promise(resolver) {
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if (typeof resolver !== 'function') {
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throw new TypeError('Promise resolver ' + resolver + ' is not a function');
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}
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if (this instanceof Promise === false) {
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throw new TypeError('Failed to construct \'Promise\': Please use the \'new\' operator, this object constructor cannot be called as a function.');
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}
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this._then = [];
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invokeResolver(resolver, this);
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}
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Promise.prototype = {
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constructor: Promise,
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_state: PENDING,
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_then: null,
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_data: undefined,
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_handled: false,
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then: function (onFulfillment, onRejection) {
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var subscriber = {
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owner: this,
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then: new this.constructor(NOOP),
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fulfilled: onFulfillment,
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rejected: onRejection
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};
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if ((onRejection || onFulfillment) && !this._handled) {
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this._handled = true;
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if (this._state === REJECTED && isNode) {
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asyncCall(notifyRejectionHandled, this);
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}
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}
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if (this._state === FULFILLED || this._state === REJECTED) {
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// already resolved, call callback async
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asyncCall(invokeCallback, subscriber);
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} else {
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// subscribe
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this._then.push(subscriber);
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}
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return subscriber.then;
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},
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catch: function (onRejection) {
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return this.then(null, onRejection);
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}
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};
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Promise.all = function (promises) {
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if (!Array.isArray(promises)) {
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throw new TypeError('You must pass an array to Promise.all().');
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}
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return new Promise(function (resolve, reject) {
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var results = [];
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var remaining = 0;
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function resolver(index) {
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remaining++;
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return function (value) {
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results[index] = value;
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if (!--remaining) {
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resolve(results);
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}
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};
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}
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for (var i = 0, promise; i < promises.length; i++) {
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promise = promises[i];
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if (promise && typeof promise.then === 'function') {
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promise.then(resolver(i), reject);
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} else {
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results[i] = promise;
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}
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}
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if (!remaining) {
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resolve(results);
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}
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});
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};
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Promise.race = function (promises) {
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if (!Array.isArray(promises)) {
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throw new TypeError('You must pass an array to Promise.race().');
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}
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return new Promise(function (resolve, reject) {
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for (var i = 0, promise; i < promises.length; i++) {
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promise = promises[i];
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if (promise && typeof promise.then === 'function') {
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promise.then(resolve, reject);
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} else {
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resolve(promise);
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}
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}
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});
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};
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Promise.resolve = function (value) {
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if (value && typeof value === 'object' && value.constructor === Promise) {
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return value;
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}
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return new Promise(function (resolve) {
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resolve(value);
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});
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};
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Promise.reject = function (reason) {
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return new Promise(function (resolve, reject) {
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reject(reason);
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});
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};
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module.exports = Promise;
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