asGoal message

"False, protocol *MicroKanren-core"
asGoal

   ^ Failed new

"True, protocol *MicroKanren-core"
asGoal

   ^ Succeed new

"BlockClosure, protocol *MicroKanren-core"
asGoal

   ^ (numArgs = 0
         ifTrue: [ Eta new ]
         ifFalse: [ Fresh new ])
        receiver: self;
        yourself