Answer a number >= 0 which represents the current version of the object’s representation. The default implementation answers zero.
This method is called if a VersionableObjectProxy is attached to a class. It receives the version number that was stored for the object (or nil if the object did not use a VersionableObjectProxy), the fixed instance variables, the indexed instance variables, and the ObjectDumper that has read the object. The default implementation ignores the version and simply fills in an instance of the receiver with the given fixed and indexed instance variables (nil if the class instances are of fixed size). If instance variables were removed from the class, extras are ignored; if the class is now fixed and used to be indexed, indexed is not used.
Answer the number of instance variables that the class used to have when objects were stored without using a VersionableObjectProxy. The default implementation answers the current instSize.