Whats the purpose of typescript's __awaiter : <p>consider this simple class</p>

<pre><code>class Test {
    private foo(): Promise&lt;void&gt; {
        return new Promise&lt;void&gt;((resolve, reject) =&gt; {
            resolve();
        });
    }

    private async bar() {
        await this.foo();
    }
}
</code></pre>

<p>This get compiled into </p>

<pre><code>var __awaiter = (this &amp;&amp; this.__awaiter) || function (thisArg, _arguments, P, generator) {
    return new (P || (P = Promise))(function (resolve, reject) {
        function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
        function rejected(value) { try { step(generator.throw(value)); } catch (e) { reject(e); } }
        function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
        step((generator = generator.apply(thisArg, _arguments)).next());
    });
};
class Test {
    foo() {
        return new Promise((resolve, reject) =&gt; {
            resolve();
        });
    }
    bar() {
        return __awaiter(this, void 0, void 0, function* () {
            yield this.foo();
        });
    }
}
//# sourceMappingURL=Test.js.map
</code></pre>

<p>but ES6 supports the keyword await natively, why would typescript get rid of await and return another Promise wrapper? </p>

<p>Whats the purpose of __awaiter </p>
