




The function 
reuse-interfaces-p
 is the predicate for whether global interface re-use is enabled. 
The function 
(setf reuse-interfaces-p)
 enables or disables global interface re-use.
If global re-use is enabled, then locate-interface and find-interface may return existing interfaces. If global re-use is disabled, then locate-interface returns 
nil
 and find-interface returns a new interface.