Join2Fits(object1, object2)model slot to determine what kind of object is to be created and returned. If both objects have "MCL", then an object of class "MCLFit" is created; if one has "GMCL" and one has "MCL", then an object of class "GMCLFit" is created, where the one with "GMCL" is assumed to come from the first development periods; if both have "GMCL", then an object of class "GMCLFit" is created.MultiChainLadder