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node_modules/core-js/internals/array-unique-by.js

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+'use strict';
+var uncurryThis = require('../internals/function-uncurry-this');
+var aCallable = require('../internals/a-callable');
+var isNullOrUndefined = require('../internals/is-null-or-undefined');
+var lengthOfArrayLike = require('../internals/length-of-array-like');
+var toObject = require('../internals/to-object');
+var MapHelpers = require('../internals/map-helpers');
+var iterate = require('../internals/map-iterate');
+
+var Map = MapHelpers.Map;
+var mapHas = MapHelpers.has;
+var mapSet = MapHelpers.set;
+var push = uncurryThis([].push);
+
+// `Array.prototype.uniqueBy` method
+// https://github.com/tc39/proposal-array-unique
+module.exports = function uniqueBy(resolver) {
+  var that = toObject(this);
+  var length = lengthOfArrayLike(that);
+  var result = [];
+  var map = new Map();
+  var resolverFunction = !isNullOrUndefined(resolver) ? aCallable(resolver) : function (value) {
+    return value;
+  };
+  var index, item, key;
+  for (index = 0; index < length; index++) {
+    item = that[index];
+    key = resolverFunction(item);
+    if (!mapHas(map, key)) mapSet(map, key, item);
+  }
+  iterate(map, function (value) {
+    push(result, value);
+  });
+  return result;
+};