This Julia package is part of the StateSpaceEcon ecosystem. ModelBaseEcon contains the basic elements needed for model definition. StateSpaceEcon works with model objects defined with ModelBaseEcon.
Since the three packages are tightly integrated with, you should include all three into your Julia environment.
] add StateSpaceEcon ModelBaseEcon TimeSeriesEconCombined documentation and tutorials for all packages part of StateSpaceEcon is located here.