Special new data type for no-default. Not often needed by the end-user, mainly internal.
NO_DEF: Singleton object for type, used inDomainwhen no default is given.is_nodefault(): Is an object the 'no default' object?
Special new data type for no-default. Not often needed by the end-user, mainly internal.
NO_DEF: Singleton object for type, used in Domain when no default is given.
is_nodefault(): Is an object the 'no default' object?