len

src/daglib/dag.py

@@ -58,7 +58,7 @@ class DAG(Generic[T], MutableMapping[T, MutableSet[T]]):
         return iter(self._succ)
 
     def __len__(self) -> int:
-        return len(self._succ)
+        return sum(map(len, self._succ.values()))
 
     def __repr__(self) -> str:
         return f"{self.__class__.__name__}{dict(self._succ)!r}"

src/daglib/set.py

@@ -52,7 +52,7 @@ class DAGSet(MutableSet[T]):
     def discard(self, v: T) -> None:
         self._data.discard(v)
         if self.on_remove:
-            self.on_remove()
+            self.on_remove(v)
 
     # --- in-place operator support ---