asp.net mvc core - equivalent of User.IsSignedIn()
<p>I am migrating a web application over to the new <code>asp.net core</code> model, and have hit a sudden snag with one of the views.</p>

<p>I cannot find the migrated equivalent to <code>User</code> and <code>User.IsSignedIn()</code> under the new model - when used in views, like this...</p>

<pre><code>@using System.Security.Claims
@if (User.IsSignedIn())
{
}
</code></pre>

<p>I've tried importing the <code>Microsoft.AspNetCore.Mvc.Razor</code> library, where I thought it would be held, but it doesn't seem to work that way.</p>