&key error-if-not-found?)
(bind ((v1 (find-vertex graph value-1 error-if-not-found?))
(v2 (find-vertex graph value-2 error-if-not-found?)))
- (aif (and v1 v2 (find-edge-between-vertexes-if graph v1 v2 fn))
- it
- (when error-if-not-found?
- (error 'graph-edge-not-found-error :vertex-1 v1 :vertex-2 v2)))))
+ (or (and v1 v2 (find-edge-between-vertexes-if graph v1 v2 fn))
+ (when error-if-not-found?
+ (error 'graph-edge-not-found-error :vertex-1 v1 :vertex-2 v2)))))
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