anchor.diff:              solution 
               |> Map.add head.Package x
             let nextDependencies = 
  -            dependencies 
  +            // dependencies
  +            tail
  +            |> Set.ofSeq 
               |> Set.union x.Manifest.Dependencies
             let nextVisited = visited |> Set.add x.Location
             step sourceManager (nextSolution, nextDependencies, nextVisited)
  
positive.code:         |> Seq.filter (fun x -> x |> Constraint.satisfies head.Constraint)
          |> Seq.filter (fun x -> 
            dependencies 
            |> Seq.exists (fun y -> x |> Constraint.agreesWith y.Constraint |> not) 
            |> not
          )
  
negative.code:       unsatisfied solution dependencies
        |> List.sortBy (fun x -> constraintSearchCost x.Constraint)
      match pending with
      | head :: tail -> 
        System.Console.WriteLine("Processing " + (Dependency.show head) + "... ")
        let! versions = sourceManager.FetchVersions head.Package
        let compatibleVersions = 
  