the <code class="json">Value</code> of the latter is decoded as a list of symbols which must name existing classes <var>L<sub>1</sub></var>, ... <var>L<sub>n</sub></var>, <var>n</var> &ge; 0.  The encompassing <code class="json">Object</code>, <var>D</var>, is then decoded to a fluid object <var>F</var> whose class <var>K</var> has all the classes <var>L<sub>1</sub></var>, ... <var>L<sub>n</sub></var> as its direct superclasses.  Unless any of the classes <var>L<sub>1</sub></var>, ... <var>L<sub>n</sub></va