anchor.diff:  
   [[layer:Cycles]]
   .There must be no cyclic dependencies between layers.
  -[source,cypher,role=constraint,requiresConcepts="layer:ExistingRelations"]
  +[source,cypher,role=constraint,requiresConcepts="layer:ExistingRelations, layer:WantedRelations"]
   ----
   MATCH
     (L1:Layer)-[sr:LAYER_USE]->(L2:Layer),
  
positive.code: 
  [[layer:ExistingRelations]]
  .Adds the relation `LAYER_USE` for all Layers which contains classes which depends on each other. Add the information `allowed`, `count` (nr of dependencies), `dependencies`.
  [source,cypher,role=concept,requiresConcepts="layer:Layer"]
  ----
  MATCH
      (L1:Layer)-[:CONTAINS*]->(t1:Type),
  
negative.code:  (service:Layer{name:"service"}),
   (util:Layer{name:"util"})
  MERGE
   (constraints)-[:LAYER_USE{allowed:true}]->(util)
  MERGE
   (config)-[:LAYER_USE{allowed:true}]->(security)
  MERGE
  