The way I work is, I make an interface{} red-black-tree, and then when I need to store things in it I create functions around it.
Suppose I'm storing Tiles in a Level: the Level struct will contain a (private) RedBlackTree and I'll define GetTile(Pos) Tile and PutTile(Pos, Tile) on Level which do the casting to and from interface{}.
I still have type safety since I cannot put/get anything but Tiles in the RedBlackTree. But I didn't need generics.
Suppose I'm storing Tiles in a Level: the Level struct will contain a (private) RedBlackTree and I'll define GetTile(Pos) Tile and PutTile(Pos, Tile) on Level which do the casting to and from interface{}.
I still have type safety since I cannot put/get anything but Tiles in the RedBlackTree. But I didn't need generics.