TFuture as a Type. Requires Template Argument List

Hi everyone.

I am currently exploring TFutures in Unreal and I am having a little bit of difficulty getting started.
Essentially I cannot get VS to recognize TFuture as a type.

Errors:

‘TFuture’: use of class template requires template argument list

Argument list for class template “TFuture” is missing.

Unfortunately, there is very little documentation about TFutures, so I am flying blind here.
I have explored AsycTest.cpp suggested from here:
https://forums.unrealengine.com/development-discussion/engine-source-github/27216-new-core-feature-async-framework-master-branch-and-4-8

Template: TFuture< ResultType & > | Unreal Engine Documentation

I am using this utility as an example, however, I cannot see how they added the template arguments: https://www.ue4community.wiki/legacy/asynchronous-image-loading-from-disk-dti6xxg9

Admittedly, I do have limited experience using templates, so I am pretty sure this is a problem between keyboard and chair.

TLDR: What do I need to add to my class in order to use TFuture as a type.

Any help would be greatly appreciated.

Kind regards

Alex