diff --git a/qupsy/language.py b/qupsy/language.py
index bbebd49..149da6a 100644
--- a/qupsy/language.py
+++ b/qupsy/language.py
@@ -34,9 +34,9 @@ def depth(self) -> int:
         )
 
     @property
-    def filled(self) -> bool:
+    def terminated(self) -> bool:
         for aexp in self.children:
-            if not aexp.filled:
+            if not aexp.terminated:
                 return False
         return True
 
@@ -104,7 +104,7 @@ def children(self) -> list[Aexp]:
         return []
 
     @property
-    def filled(self) -> bool:
+    def terminated(self) -> bool:
         return False
 
 
@@ -227,9 +227,9 @@ def depth(self) -> int:
         )
 
     @property
-    def filled(self) -> bool:
+    def terminated(self) -> bool:
         for aexp in self.children:
-            if not aexp.filled:
+            if not aexp.terminated:
                 return False
         return True
 
@@ -253,7 +253,7 @@ def children(self) -> list[Aexp]:
         return []
 
     @property
-    def filled(self) -> bool:
+    def terminated(self) -> bool:
         return False
 
 
@@ -410,9 +410,9 @@ def depth(self) -> int:
         )
 
     @property
-    def filled(self) -> bool:
+    def terminated(self) -> bool:
         for child in self.children:
-            if not child.filled:
+            if not child.terminated:
                 return False
         return True
 
@@ -436,7 +436,7 @@ def children(self) -> list[Cmd | Gate | Aexp]:
         return []
 
     @property
-    def filled(self) -> bool:
+    def terminated(self) -> bool:
         return False
 
 
diff --git a/qupsy/transition.py b/qupsy/transition.py
index 52024de..35e3759 100644
--- a/qupsy/transition.py
+++ b/qupsy/transition.py
@@ -36,7 +36,7 @@ def visit_Aexp(self, aexp: Aexp) -> list[Aexp]:
             return visitor(aexp)
 
         for i, child in enumerate(aexp.children):
-            if child.filled:
+            if child.terminated:
                 continue
             next_children = self.visit_Aexp(child)
             pre_args = aexp.children[:i]
@@ -50,7 +50,7 @@ def visit_Aexp(self, aexp: Aexp) -> list[Aexp]:
                         *(a.copy() for a in post_args),
                     )
                 )
-
+            return ret
         return []
 
     def visit_HoleGate(self, gate: HoleGate) -> list[Gate]:
@@ -63,7 +63,7 @@ def visit_Gate(self, gate: Gate) -> list[Gate]:
             return visitor(gate)
 
         for i, child in enumerate(gate.children):
-            if child.filled:
+            if child.terminated:
                 continue
             next_children = self.visit_Aexp(child)
             pre_args = gate.children[:i]
@@ -84,13 +84,13 @@ def visit_HoleCmd(self, cmd: HoleCmd) -> list[Cmd]:
         return [SeqCmd(), ForCmd(var=f"i{self.for_depth}"), GateCmd()]
 
     def visit_SeqCmd(self, cmd: SeqCmd) -> list[Cmd]:
-        if not cmd.pre.filled:
+        if not cmd.pre.terminated:
             pres = self.visit_Cmd(cmd.pre)
             ret: list[Cmd] = []
             for pre in pres:
                 ret.append(SeqCmd(pre=pre, post=cmd.post.copy()))
             return ret
-        if not cmd.post.filled:
+        if not cmd.post.terminated:
             posts = self.visit_Cmd(cmd.post)
             ret: list[Cmd] = []
             for post in posts:
@@ -99,7 +99,7 @@ def visit_SeqCmd(self, cmd: SeqCmd) -> list[Cmd]:
         return []
 
     def visit_ForCmd(self, cmd: ForCmd) -> list[Cmd]:
-        if not cmd.start.filled:
+        if not cmd.start.terminated:
             starts = self.visit_Aexp(cmd.start)
             ret: list[Cmd] = []
             for start in starts:
@@ -112,7 +112,7 @@ def visit_ForCmd(self, cmd: ForCmd) -> list[Cmd]:
                     )
                 )
             return ret
-        if not cmd.end.filled:
+        if not cmd.end.terminated:
             ends = self.visit_Aexp(cmd.end)
             ret: list[Cmd] = []
             for end in ends:
@@ -125,7 +125,7 @@ def visit_ForCmd(self, cmd: ForCmd) -> list[Cmd]:
                     )
                 )
             return ret
-        if not cmd.body.filled:
+        if not cmd.body.terminated:
             self.for_depth += 1
             bodies = self.visit_Cmd(cmd.body)
             self.for_depth -= 1
diff --git a/tests/test_transition.py b/tests/test_transition.py
index 21010ec..fc2a4eb 100644
--- a/tests/test_transition.py
+++ b/tests/test_transition.py
@@ -2,12 +2,14 @@
     ALL_AEXPS,
     ALL_GATES,
     CX,
+    Add,
     Aexp,
     Cmd,
     ForCmd,
     Gate,
     GateCmd,
     H,
+    HoleAexp,
     Integer,
     Pgm,
     SeqCmd,
@@ -78,3 +80,18 @@ def test_hole_aexp3():
         if type(pgm.body.gate.qreg2) not in [Integer, Var]:
             aexp_types.remove(type(pgm.body.gate.qreg2))
     assert len(aexp_types) == 3
+
+
+def test_next_aexp():
+    pgm = Pgm("n", GateCmd(CX(Integer(0), Add())))
+    aexp_types: list[type[Aexp]] = ALL_AEXPS.copy()
+    pgms = next(pgm)
+    for pgm in pgms:
+        assert isinstance(pgm.body, GateCmd)
+        assert isinstance(pgm.body.gate, CX)
+        assert isinstance(pgm.body.gate.qreg2, Add)
+        assert type(pgm.body.gate.qreg2.a) in aexp_types
+        if type(pgm.body.gate.qreg2.a) not in [Integer, Var]:
+            aexp_types.remove(type(pgm.body.gate.qreg2.a))
+        assert isinstance(pgm.body.gate.qreg2.b, HoleAexp)
+    assert len(aexp_types) == 3