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node_modules/core-js/internals/collection-from.js

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+'use strict';
+// https://tc39.github.io/proposal-setmap-offrom/
+var bind = require('../internals/function-bind-context');
+var call = require('../internals/function-call');
+var aCallable = require('../internals/a-callable');
+var aConstructor = require('../internals/a-constructor');
+var isNullOrUndefined = require('../internals/is-null-or-undefined');
+var iterate = require('../internals/iterate');
+
+var push = [].push;
+
+module.exports = function from(source /* , mapFn, thisArg */) {
+  var length = arguments.length;
+  var mapFn = length > 1 ? arguments[1] : undefined;
+  var mapping, array, n, boundFunction;
+  aConstructor(this);
+  mapping = mapFn !== undefined;
+  if (mapping) aCallable(mapFn);
+  if (isNullOrUndefined(source)) return new this();
+  array = [];
+  if (mapping) {
+    n = 0;
+    boundFunction = bind(mapFn, length > 2 ? arguments[2] : undefined);
+    iterate(source, function (nextItem) {
+      call(push, array, boundFunction(nextItem, n++));
+    });
+  } else {
+    iterate(source, push, { that: array });
+  }
+  return new this(array);
+};