How can I check if a plugin is installed and enabled, in Craft 3? In a question I asked a few years ago, it was very simple to perform a check on wether a plugin was installed or not. 

As of Craft 3, the same methods don't seem to work. The likes of this always returns true: 

{{ craft.myPlugin is defined ? 'Installed' : 'Not Installed' }}


Is there another way to determine if a specific plugin is installed and enabled?
PHP

\Craft::$app-&gt;plugins-&gt;isPluginInstalled('plugin-handle')


Twig

{% set installed = craft.app.plugins.isPluginInstalled('plugin-handle') %}


There is also a isPluginDisabled and a isPluginEnabled function.
Here is a class reference craft\services\Plugins