diff --git a/src/eqx.py b/src/eqx.py
index e05ea5b..08add64 100644
--- a/src/eqx.py
+++ b/src/eqx.py
@@ -77,12 +77,12 @@ def sow(where: Callable, model: eqx.Module) -> eqx.Module:
                 activ.append(x)
                 return x
 
-            return eqx.filter_jit(store_activation)
+            return store_activation
 
     model = eqx.tree_at(where, model, replace_fn=install_sow)
 
     model_call = type(model).__call__
-    todo("make Sow a generic class")
+    todo("make Sow a generic class, also don't have nested Sows but check whether model is already a sow.")
 
     class Sow(type(model)):
         def __init__(self, model):
@@ -91,7 +91,10 @@ def sow(where: Callable, model: eqx.Module) -> eqx.Module:
         def __call__(self, *args, **kwargs):
             activ.clear()  # empty the list
             x = model_call(self, *args, **kwargs)
-            return activ + [x]
+            if isinstance(x, list):
+                return activ + x
+            else:
+                return activ + [x]
 
     return Sow(model)
 
diff --git a/src/store.py b/src/store.py
new file mode 100644
index 0000000..c5b34bd
--- /dev/null
+++ b/src/store.py
@@ -0,0 +1,115 @@
+from hashlib import sha256
+import inspect
+import json
+from pathlib import Path
+import pickle
+
+
+def arg_filtering(large_fn, small_fn):
+    large_sig, small_sig = inspect.signature(large_fn), inspect.signature(small_fn)
+    large_keys =  tuple(large_sig.parameters.keys())
+
+    # Create a mapping from small_fn's positional arguments to large_fn's positional arguments.
+    indices = []
+    for i, (key, value) in enumerate(small_sig.parameters.items()):
+        if value.kind not in (value.POSITIONAL_OR_KEYWORD, value.POSITIONAL_ONLY):
+            
+            continue
+
+        try:
+            print(large_keys.index(key))
+            i = large_keys.index(key)
+        # If an argument from small_fn is not present in large_fn, just note the index of that
+        # argument as it is in small_fn.
+        except ValueError:
+            print("not found")
+
+        assert i not in indices
+        indices.append(i)
+
+    # Enumerate all small_fn's keyword arguments.
+    filter_kwargs = {param.name for param in small_sig.parameters.values() 
+                     if param.kind == param.POSITIONAL_OR_KEYWORD 
+                     or param.kind == param.KEYWORD_ONLY}
+
+    def inner(*raw_args, **raw_kwargs):
+        # For each argument in small_fn, find the argument's value from large_fn by index.
+        args = []
+        for i in indices:
+            if i >= len(raw_args):
+                break
+            args.append(raw_args[i])
+
+        # Filter any keyword arguments not present in small_fn.
+        kwargs = {k: v for k, v in raw_kwargs.items() if k in filter_kwargs}
+
+        return small_fn(*args, **kwargs)
+
+    return inner
+
+
+class load_or_create:
+
+    def __init__(
+        self,
+        load=pickle.load,
+        save=pickle.dump,
+        prefix="./",
+        suffix=".pkl",
+        hash_len=8,
+        save_args=False,
+        plain_text=False
+    ):
+        self.load=load
+        self.save=save
+        self.prefix=prefix
+        self.suffix=suffix
+        self.hash_len=hash_len
+        self.save_args=save_args
+        self.plain_text=plain_text
+        self.not_called=True
+
+    def __call__(self, fn):
+        assert self.not_called
+        self.not_called = False
+
+        fn_args = tuple(inspect.signature(fn).parameters.keys())
+
+        self.load = arg_filtering(fn, self.load)
+        self.save = arg_filtering(fn, self.save)
+
+        def inner(*args, **kwargs):
+            # Store all arguments into json and hash it to get the storage path.
+            json_args = (
+                json.dumps(
+                    (args, kwargs),
+                    default=lambda x: vars(x) if hasattr(x, "__dict__") else str(x)
+                ) + "\n"
+            ).encode("utf-8")
+            hash = sha256(json_args, usedforsecurity=False).hexdigest()[:self.hash_len]
+            path = Path(self.prefix + hash + self.suffix)
+
+            for i, arg in enumerate(args):
+                kwargs[fn_args[i]] = arg
+
+            # If the path exists, load the object from there.
+            if path.exists():
+                with open(path, "r" if self.plain_text else "rb") as f:
+                   if self.save_args:
+                       f.readline()
+                   return self.load(f, **kwargs)
+
+            # Else, run the function and store its result.
+            out = fn(**kwargs)
+
+            if "/" in self.suffix:
+                path.parent.mkdir(parents=True)
+            with open(path, "w" if self.plain_text else "wb") as f:
+                if self.save_args:
+                    f.write(json_args)
+                self.save(f, out, **kwargs)
+
+            return out
+
+        return inner
+