+The only reasons we rely on cl-mathstats are
+
+; /Users/gwking/.fasls/allegro-8.0m-macosx-x86/Users/gwking/darcs/cl-graph/dev/graphviz/graphviz-support.fasl
+Warning: While compiling these undefined functions were referenced:
+ cl-graph::matrix-trace from position 7424 in
+ /Users/gwking/darcs/cl-graph/dev/graph-metrics.lisp
+ cl-graph::matrix-multiply from position 7424 in
+ /Users/gwking/darcs/cl-graph/dev/graph-metrics.lisp, 7827 in
+ /Users/gwking/darcs/cl-graph/dev/graph-metrics.lisp
+ cl-graph::normalize-matrix from position 7424 in
+ /Users/gwking/darcs/cl-graph/dev/graph-metrics.lisp
+
+;;; move to l0-arrays? or metatilities?
+ cl-graph:: sum-of-array-elements from position 7424 in
+ /Users/gwking/darcs/cl-graph/dev/graph-metrics.lisp, 7827 in
+ /Users/gwking/darcs/cl-graph/dev/graph-metrics.lisp
+ cl-graph::combination-count from position 5742 in
+ /Users/gwking/darcs/cl-graph/dev/graph-metrics.lisp
+
+some other things might be +e+, degrees->radians and radians->degrees,
+ combination-count, permutation-count, sum-of-array-elements
+
+
+- Use samep in samep for associative containers
+
+optimize : find-edge-between-vertexes-if
+(defmethod find-edge-between-vertexes-if ((graph graph-container)
+ (vertex-1 graph-container-vertex)
+ (value-2 t)
+ fn
+ &key error-if-not-found?)
+ (let ((v2 (find-vertex graph value-2 error-if-not-found?)))
+ (when v2
+ (find-edge-between-vertexes-if
+ graph vertex-1 v2 fn
+ :error-if-not-found? error-if-not-found?))))
+
+;;; ---------------------------------------------------------------------------
+
+(defmethod find-edge-between-vertexes-if ((graph graph-container)
+ (value-1 t)
+ (vertex-2 graph-container-vertex)
+ fn
+ &key error-if-not-found?)
+ (let ((v1 (find-vertex graph value-1 error-if-not-found?)))
+ (when v1
+ (find-edge-between-vertexes-if
+ graph v1 vertex-2 fn
+ :error-if-not-found? error-if-not-found?))))
+
+
+Hmm, should probably write a macro that created all four method [ (t t), (t vertex), (vertex t) and (vertex vertex)] magically...
+
+
+Should have delete-item-at-1
+
+delete-edge : equal or eql
+
+