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node_modules/core-js/internals/symbol-is-well-known.js

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+'use strict';
+var shared = require('../internals/shared');
+var getBuiltIn = require('../internals/get-built-in');
+var uncurryThis = require('../internals/function-uncurry-this');
+var isSymbol = require('../internals/is-symbol');
+var wellKnownSymbol = require('../internals/well-known-symbol');
+
+var Symbol = getBuiltIn('Symbol');
+var $isWellKnownSymbol = Symbol.isWellKnownSymbol;
+var getOwnPropertyNames = getBuiltIn('Object', 'getOwnPropertyNames');
+var thisSymbolValue = uncurryThis(Symbol.prototype.valueOf);
+var WellKnownSymbolsStore = shared('wks');
+
+for (var i = 0, symbolKeys = getOwnPropertyNames(Symbol), symbolKeysLength = symbolKeys.length; i < symbolKeysLength; i++) {
+  // some old engines throws on access to some keys like `arguments` or `caller`
+  try {
+    var symbolKey = symbolKeys[i];
+    if (isSymbol(Symbol[symbolKey])) wellKnownSymbol(symbolKey);
+  } catch (error) { /* empty */ }
+}
+
+// `Symbol.isWellKnownSymbol` method
+// https://tc39.es/proposal-symbol-predicates/#sec-symbol-iswellknownsymbol
+// We should patch it for newly added well-known symbols. If it's not required, this module just will not be injected
+module.exports = function isWellKnownSymbol(value) {
+  if ($isWellKnownSymbol && $isWellKnownSymbol(value)) return true;
+  try {
+    var symbol = thisSymbolValue(value);
+    for (var j = 0, keys = getOwnPropertyNames(WellKnownSymbolsStore), keysLength = keys.length; j < keysLength; j++) {
+      if (WellKnownSymbolsStore[keys[j]] == symbol) return true;
+    }
+  } catch (error) { /* empty */ }
+  return false;
+};