Async await function error

I am using WonderPush in a Flutter App. When I use the following code:

var installationId = await WonderPush.getInstallationId();

I get the following error:

The await expression can only be used in an async function.
Try marking the function body with either ‘async’ or 'async’.*

When I remove the await keyword, the error goes away but when I print installationId I get the following value: Instance of 'Future’

My app needs to be able to send notifications to individual installations so I am currently at a loss on what to do here.