-To prevent any clash between different magics defined with this module, an unique numerical signature is attached to each kind of magic (i.e. each set of callbacks for magic operations).
-At the C level, magic tokens owned by magic created by this module have their C<< mg->mg_private >> field set to C<0x3891> or C<0x3892>, so please don't use these magic (sic) numbers in other extensions.
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