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node_modules/core-js/modules/esnext.observable.from.js

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+'use strict';
+var $ = require('../internals/export');
+var getBuiltIn = require('../internals/get-built-in');
+var call = require('../internals/function-call');
+var anObject = require('../internals/an-object');
+var isConstructor = require('../internals/is-constructor');
+var getIterator = require('../internals/get-iterator');
+var getMethod = require('../internals/get-method');
+var iterate = require('../internals/iterate');
+var wellKnownSymbol = require('../internals/well-known-symbol');
+var OBSERVABLE_FORCED = require('../internals/observable-forced');
+
+var $$OBSERVABLE = wellKnownSymbol('observable');
+
+// `Observable.from` method
+// https://github.com/tc39/proposal-observable
+$({ target: 'Observable', stat: true, forced: OBSERVABLE_FORCED }, {
+  from: function from(x) {
+    var C = isConstructor(this) ? this : getBuiltIn('Observable');
+    var observableMethod = getMethod(anObject(x), $$OBSERVABLE);
+    if (observableMethod) {
+      var observable = anObject(call(observableMethod, x));
+      return observable.constructor === C ? observable : new C(function (observer) {
+        return observable.subscribe(observer);
+      });
+    }
+    var iterator = getIterator(x);
+    return new C(function (observer) {
+      iterate(iterator, function (it, stop) {
+        observer.next(it);
+        if (observer.closed) return stop();
+      }, { IS_ITERATOR: true, INTERRUPTED: true });
+      observer.complete();
+    });
+  }
+});