anchor.diff:      lists_some(F, Args, false).
   
   -spec lists_some(evaluator(A, Return, FailIndicator), [A], FailIndicator) ->
  -                       Return | FailIndicator.
  +                        Return | FailIndicator.
   lists_some(_, [], False) ->
       False;
   lists_some(F, [H | T], False) ->
  
positive.code:     Pkg3Deps = [{app5, "2.0.0", '>='}],
  
      Dom0 = add_packages(new_graph(), [{app1, [{"0.1.0", Pkg1Deps},
                                         {"0.1.0", Pkg1Deps},
                                         {"0.2", Pkg1Deps},
                                         {"3.0", Pkg1Deps}]},
                                 {app2, [{"0.0.1", Pkg2Deps},
                                         {"0.1", Pkg2Deps},
                                         {"1.0", Pkg2Deps},
                                         {"3.0", Pkg2Deps}]},
                                 {app3, [{"0.1.0", Pkg3Deps},
                                         {"0.1.3", Pkg3Deps},
                                         {"2.0.0", Pkg3Deps},
                                         {"3.0.0", Pkg3Deps},
                                         {"4.0.0", Pkg3Deps}]},
                                 {app4, [{"0.1.0", [{app5, "0.1.0"}]},
                                         {"0.3.0", [{app5, "0.3.0"}]},
                                         {"5.0.0", [{app5, "2.0.0"}]},
                                         {"6.0.0", [{app5, "6.0.0"}]}]},
                                 {app5, [{"0.1.0", []},
                                         {"0.3.0", []},
                                         {"2.0.0", []},
                                         {"6.0.0", []}]}]),
  
      ?assertMatch({ok, [{app5,{2,0,0}},
                         {app3,{0,1,3}},
  
negative.code: 
  
      Dom0 = add_packages(new_graph(), [{app1, [{"3.0", Pkg1Deps}]},
                                        {app2, [{"0.0.1", Pkg2Deps}]},
                                        {app3, [{"0.1.0", Pkg3Deps}]},
                                        {app4, [{"5.0.0", [{app5, "2.0.0"}]}]},
                                        {app5, [{"2.0.0", []},
                                                {"6.0.0", []}]}]),
  
      ?assertMatch({error, {unable_to_solve,app3,{[],[],[app1,app3]}}},
                   solve(Dom0, [app1, app3])).
  