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node_modules/core-js/modules/esnext.weak-map.emplace.js

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+'use strict';
+var $ = require('../internals/export');
+var aWeakMap = require('../internals/a-weak-map');
+var WeakMapHelpers = require('../internals/weak-map-helpers');
+
+var get = WeakMapHelpers.get;
+var has = WeakMapHelpers.has;
+var set = WeakMapHelpers.set;
+
+// `WeakMap.prototype.emplace` method
+// https://github.com/tc39/proposal-upsert
+$({ target: 'WeakMap', proto: true, real: true, forced: true }, {
+  emplace: function emplace(key, handler) {
+    var map = aWeakMap(this);
+    var value, inserted;
+    if (has(map, key)) {
+      value = get(map, key);
+      if ('update' in handler) {
+        value = handler.update(value, key, map);
+        set(map, key, value);
+      } return value;
+    }
+    inserted = handler.insert(key, map);
+    set(map, key, inserted);
+    return inserted;
+  }
+});