className(class, package) packageSlot(object)
| class | a character string identifying a class. | 
| package | a character string identifying a package. If this is not given, then the function uses the package associated with the class named by class. | 
| object | any object. | 
className("numeric")
## a className object with class "numeric" and package "methods"
className("numeric", "pkg")
## a className object with class "numeric" and package "pkg"
packageSlot(className("numeric", "pkg"))
## "pkg"