Question Getting the StateMachine that runs the Unit

How do I get the StateMachine component that is running the custom unit from code?

I don't want to link up a This unit. I am using the visual scripting tool only as a graph editor to allow modularization of different RPG ability steps. Essentially, I am only connecting the enterstate and exitstate to a custom unit and let the code handle everything. Hence I need to be able to do that in a custom unit.

I see the implementation of the This unit does what I want. But I don't have access to the source code.