(and (>= *delivery-level* 3)
(not (member (delivery-value :keep-clos)
'(t
:full-dynamic-definition
:method-dynamic-definition))))
If this is non-nil, generic functions with single methods and simple arguments are collapsed -- that is, replaced by ordinary functions.
Note: Methods cannot be added to collapsed generic functions, since after their collapse to ordinary functions the generic functions definitions are deleted.
LispWorks Delivery User Guide - 10 Aug 2017