simplify the implementation

pyk/src/pyk/kcfg/kcfg.py

@@ -1044,16 +1044,15 @@ def create_split_by_nodes(self, source_id: NodeIdLike, target_ids: Iterable[Node
         """Create a split without crafting a CSubst."""
         source = self.node(source_id)
         targets = [self.node(nid) for nid in target_ids]
-        substs = [source.cterm.config.match(target.cterm.config) for target in targets]
         csubsts: list[CSubst] = []
-        if None in substs:
-            return None
-        for subst, target in zip(substs, targets, strict=True):
-            constraints: list[KInner] = []
-            for c in target.cterm.constraints:
-                if c not in source.cterm.constraints:
-                    constraints.append(c)
+
+        for target in targets:
+            subst = source.cterm.config.match(target.cterm.config)
+            if subst is None:
+                return None
+            constraints = [c for c in target.cterm.constraints if c not in source.cterm.constraints]
             csubsts.append(CSubst(subst, constraints))
+
         return self.create_split(source.id, zip(target_ids, csubsts, strict=True))
 
     def ndbranches(self, *, source_id: NodeIdLike | None = None, target_id: NodeIdLike | None = None) -> list[NDBranch]: