- (:documentation "Finds and returns an edge between value-or-vertex-1
- and value-or-vertex-2 if one exists. Unless error-if-not-found? is
- nil, then a error will be signaled. [?? Error not signal, need
- test.]"))
+ (:documentation
+ "Finds and returns an edge between value-or-vertex-1
+and value-or-vertex-2 which returns true (as a generalized boolean) when
+evaluated by `fn`. Unless error-if-not-found? is nil, then a error will
+be signaled. [?? IS error really signaled? need a test.]"))