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var wellKnownSymbol = require('../internals/well-known-symbol');
var create = require('../internals/object-create');
var definePropertyModule = require('../internals/object-define-property');
var UNSCOPABLES = wellKnownSymbol('unscopables');
var ArrayPrototype = Array.prototype;
// Array.prototype[@@unscopables]
// https://tc39.github.io/ecma262/#sec-array.prototype-@@unscopables
if (ArrayPrototype[UNSCOPABLES] == undefined) {
definePropertyModule.f(ArrayPrototype, UNSCOPABLES, {
configurable: true,
value: create(null)
});
}
// add a key to Array.prototype[@@unscopables]
module.exports = function (key) {
ArrayPrototype[UNSCOPABLES][key] = true;
};