@ - pushes the builtin object onto the stack:
  ' - symbol builder (quote)
  object - base object

% - special messages
%inherit - converts an object into an object with "add-method" and "done" methods

[code] - creates a code object (function) with an "exec" method


for example,
    @'foo [foo code] @object %inherit add-method done
creates a class that can create an object to handle a message, namely "foo".