Skeleton implementation of the "Acyclic Visitor" design pattern. This class is empty as each "node
visitor" must add its "visit" feature that visits the corresponding node (and each node must inherit
from VISITABLE).
For examples, look at the tools cluster of SmartEiffel.
This feature is obsolete: Don't use this feature anymore.
That's a 2.0 left-over that does not have any sense now that the type system is improved.
Just use Current instead.