




If this is 
nil
, the walker is deleted. 
If CLOS dynamic definitions are kept, by setting :keep-clos to 
:full-dynamic-definition
 or 
t
, then the walker will be kept.
If :keep-debug-mode is 
t
, 
:keep-walker
 will be set to 
t
 automatically.
Affected by: 
:keep-clos
.