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'use strict';
var $ = require('../internals/export');
var aMap = require('../internals/a-map');
var iterate = require('../internals/map-iterate');
// `Map.prototype.keyOf` method
// https://github.com/tc39/proposal-collection-methods
$({ target: 'Map', proto: true, real: true, forced: true }, {
keyOf: function keyOf(searchElement) {
var result = iterate(aMap(this), function (value, key) {
if (value === searchElement) return { key: key };
}, true);
return result && result.key;
}
});