> Actually, nearly all objects are specialized kinds of nodes...
>        either they have references to other objects, or they do not,
>        either other objects reference them, or not.

Actually, there are no sinks (Objects that don't point to anything)
in the Smalltalk object graph...  all objects have a reference to their
class, hidden though it is.  Even immediates (SmallIntegers) have an
encoding of bits that points to their class (effectively).

-- Mike Klein