Remove double edge insertions

examples/profiling_utilities.jl

@@ -0,0 +1,36 @@
+
+function test_random_walk(g::DAG, n::Int64)
+    # the purpose here is to do "random" operations and reverse them again and validate that the graph stays the same and doesn't diverge
+    reset_graph!(g)
+
+    properties = graph_properties(g)
+
+    for i = 1:n
+        # choose push or pop
+        if rand(Bool)
+            # push
+            opt = get_operations(g)
+
+            # choose one of fuse/split/reduce
+            option = rand(1:3)
+            if option == 1 && !isempty(opt.nodeFusions)
+                push_operation!(g, rand(collect(opt.nodeFusions)))
+            elseif option == 2 && !isempty(opt.nodeReductions)
+                push_operation!(g, rand(collect(opt.nodeReductions)))
+            elseif option == 3 && !isempty(opt.nodeSplits)
+                push_operation!(g, rand(collect(opt.nodeSplits)))
+            else
+                i = i - 1
+            end
+        else
+            # pop
+            if (can_pop(g))
+                pop_operation!(g)
+            else
+                i = i - 1
+            end
+        end
+    end
+
+    reset_graph!(g)
+end