generalize has_null_ball

diff --git a/src/prolog/machine.rs b/src/prolog/machine.rs
index 04077fe26cce0e13373ff82ae1c1eec58204ccdc..53cb6ab73e81a004b652bf601d54af77b3a03be5 100644 (file)
--- a/src/prolog/machine.rs
+++ b/src/prolog/machine.rs
@@ -1148,7 +1148,7 @@ impl MachineState {
 
     fn has_null_ball(&self) -> bool
     {
-        if let &Addr::Con(Constant::UInt64(0)) = &self.ball {
+        if let &Addr::Con(Constant::UInt64(_)) = &self.ball {
             true
         } else {
             false