dup - Duplicate the object which is on top of the stack
any dup -> any any
2 dup -> 2 2
(hello) dup -> (hello) (hello)
Raises StackUnderflow error if the stack is empty.
docu edited by Sirko Straube
/home/abuild/rpmbuild/BUILD/nest-2.20.git/sli/slistack.cc