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- 'use strict';
- var toStringTagSymbol = require('es6-symbol').toStringTag
- , toString = Object.prototype.toString
- , id = '[object WeakMap]'
- , Global = (typeof WeakMap === 'undefined') ? null : WeakMap;
- module.exports = function (x) {
- return (x && ((Global && (x instanceof Global)) ||
- (toString.call(x) === id) || (x[toStringTagSymbol] === 'WeakMap'))) ||
- false;
- };
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