The Function Node.
The Function Node is customized by the user. The number and Data Types of the Input and Output Sockets and the functionality are defined in the Node's own Logic, which is accessed by either double clicking the Node or the Function on the Function's list.
Functions can be exported and then imported in a different Project.
To add a Function, click on the add icon on the top left of the Functions tab on the left panel of the Logic Editor and type in the desired name of the Function. Then, to open the Function's Logic Graph, double-click on the Function Node. There, the Logic of the Function can be defined.
See an example in the image below.
For exporting a Function, right-click it on the Function's list or on the Node, select Export and save the Blueprints file.
For importing a Function, right-click on the Function's list or on the Logic Graph, select Import, and find the Blueprints file.