+(defknown %find-position
+ (t sequence t index sequence-end function function)
+ (values t (or index null))
+ (flushable call))
+(defknown (%find-position-if %find-position-if-not)
+ (function sequence t index sequence-end function)
+ (values t (or index null))
+ (call))
+(defknown effective-find-position-test (callable callable)
+ function
+ (flushable foldable))
+(defknown effective-find-position-key (callable)
+ function
+ (flushable foldable))