Generating fresh names in a source plugin

Hello! I want to generate AST fragments in a source plugin, and for this I need to generate fresh (local) names. My current approach is to use `mkSystemName`, but it, like many of the other name-generating operations, needs a value of type `Unique`. How can I generate such values? It seems that the `Hsc` monad doesn’t carry a value of type `UniqueSupply` with it. All the best, Wolfgang