diff --git a/Cargo.toml b/Cargo.toml
index fe5bda5..1072d77 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -16,5 +16,6 @@ thaw_components = { version = "0.2.0-alpha", path = "./thaw_components" }
 thaw_macro = { version = "0.1.0-alpha", path = "./thaw_macro" }
 thaw_utils = { version = "0.1.0-alpha", path = "./thaw_utils" }
 
-leptos = "0.7.0-beta"
-leptos_meta = "0.7.0-beta"
\ No newline at end of file
+leptos = { git = "https://github.com/leptos-rs/leptos", rev = "3dbedfc8710add4bc9a94fe27fa000fb180f393b" }
+leptos_meta = { git = "https://github.com/leptos-rs/leptos", rev = "3dbedfc8710add4bc9a94fe27fa000fb180f393b" }
+leptos_router = { git = "https://github.com/leptos-rs/leptos", rev = "3dbedfc8710add4bc9a94fe27fa000fb180f393b" }
diff --git a/demo/Cargo.toml b/demo/Cargo.toml
index c44baa8..791dfda 100644
--- a/demo/Cargo.toml
+++ b/demo/Cargo.toml
@@ -9,7 +9,7 @@ edition = "2021"
 [dependencies]
 leptos = { workspace = true }
 leptos_meta = { workspace = true }
-leptos_router = "0.7.0-beta"
+leptos_router = { workspace = true }
 thaw = { path = "../thaw" }
 demo_markdown = { path = "../demo_markdown" }
 icondata = "0.3.0"
diff --git a/thaw/src/auto_complete/mod.rs b/thaw/src/auto_complete/mod.rs
index f0fb748..a44906b 100644
--- a/thaw/src/auto_complete/mod.rs
+++ b/thaw/src/auto_complete/mod.rs
@@ -10,7 +10,7 @@ use crate::{
 use leptos::{context::Provider, either::Either, html, prelude::*};
 use std::collections::HashMap;
 use thaw_components::{Binder, Follower, FollowerPlacement, FollowerWidth};
-use thaw_utils::{class_list, mount_style, ArcOneCallback, BoxOneCallback, Model, OptionalProp};
+use thaw_utils::{class_list, mount_style, ArcOneCallback, BoxOneCallback, Model};
 
 #[slot]
 pub struct AutoCompletePrefix {
@@ -25,7 +25,7 @@ pub struct AutoCompleteSuffix {
 #[component]
 pub fn AutoComplete(
     #[prop(optional, into)] value: Model<String>,
-    #[prop(optional, into)] placeholder: OptionalProp<MaybeSignal<String>>,
+    #[prop(optional, into)] placeholder: MaybeProp<String>,
     #[prop(optional, into)] clear_after_select: MaybeSignal<bool>,
     #[prop(optional, into)] blur_after_select: MaybeSignal<bool>,
     #[prop(optional, into)] on_select: Option<BoxOneCallback<String>>,
diff --git a/thaw/src/input/mod.rs b/thaw/src/input/mod.rs
index e431d72..34c0133 100644
--- a/thaw/src/input/mod.rs
+++ b/thaw/src/input/mod.rs
@@ -24,7 +24,7 @@ pub fn Input(
     #[prop(optional, into)] input_type: MaybeSignal<InputType>,
     /// Placeholder text for the input.
     #[prop(optional, into)]
-    placeholder: OptionalProp<MaybeSignal<String>>,
+    placeholder: MaybeProp<String>,
     #[prop(optional, into)] on_focus: Option<BoxOneCallback<ev::FocusEvent>>,
     #[prop(optional, into)] on_blur: Option<BoxOneCallback<ev::FocusEvent>>,
     /// Whether the input is disabled
@@ -165,7 +165,7 @@ pub fn Input(
                 on:blur=on_internal_blur
                 class="thaw-input__input"
                 disabled=move || disabled.get()
-                placeholder=placeholder.map(|p| move || p.get())
+                placeholder=move || placeholder.get()
                 node_ref=input_ref
             />
 
diff --git a/thaw/src/menu/menu_item.rs b/thaw/src/menu/menu_item.rs
index 12ad46e..ebb2f7f 100644
--- a/thaw/src/menu/menu_item.rs
+++ b/thaw/src/menu/menu_item.rs
@@ -4,11 +4,11 @@ use crate::{
 };
 use leptos::prelude::*;
 use thaw_components::{Fallback, If, OptionComp, Then};
-use thaw_utils::{class_list, mount_style, OptionalMaybeSignal};
+use thaw_utils::{class_list, mount_style};
 
 #[component]
 pub fn MenuItem(
-    #[prop(optional, into)] icon: OptionalMaybeSignal<icondata_core::Icon>,
+    #[prop(optional, into)] icon: MaybeProp<icondata_core::Icon>,
     #[prop(into)] value: MaybeSignal<String>,
     #[prop(optional, into)] disabled: MaybeSignal<bool>,
     #[prop(optional, into)] class: MaybeProp<String>,
diff --git a/thaw/src/menu/mod.rs b/thaw/src/menu/mod.rs
index 8d7fe02..4c637ed 100644
--- a/thaw/src/menu/mod.rs
+++ b/thaw/src/menu/mod.rs
@@ -7,14 +7,13 @@ use leptos::{ev, html::Div, leptos_dom::helpers::TimeoutHandle, prelude::*};
 use std::time::Duration;
 use thaw_components::{Binder, CSSTransition, Follower, FollowerPlacement};
 use thaw_utils::{
-    add_event_listener, call_on_click_outside, class_list, mount_style, ArcOneCallback,
-    BoxCallback, OptionalProp,
+    add_event_listener, call_on_click_outside, class_list, mount_style, ArcOneCallback, BoxCallback,
 };
 
 #[slot]
 pub struct MenuTrigger {
     #[prop(optional, into)]
-    class: OptionalProp<MaybeSignal<String>>,
+    class: MaybeProp<String>,
     children: Children,
 }
 
@@ -103,7 +102,7 @@ pub fn Menu(
     view! {
         <Binder target_ref>
             <div
-                class=class_list!["thaw-menu-trigger", trigger_class.map(| c | move || c.get())]
+                class=class_list!["thaw-menu-trigger", trigger_class]
                 node_ref=target_ref
                 on:mouseenter=on_mouse_enter
                 on:mouseleave=on_mouse_leave
diff --git a/thaw/src/space/mod.rs b/thaw/src/space/mod.rs
index e84b2aa..fb6c1e0 100644
--- a/thaw/src/space/mod.rs
+++ b/thaw/src/space/mod.rs
@@ -1,5 +1,5 @@
 use leptos::prelude::*;
-use thaw_utils::{class_list, mount_style, OptionalMaybeSignal};
+use thaw_utils::{class_list, mount_style};
 
 #[derive(Default)]
 pub enum SpaceGap {
@@ -16,8 +16,8 @@ pub enum SpaceGap {
 pub fn Space(
     #[prop(optional)] gap: SpaceGap,
     #[prop(optional)] vertical: bool,
-    #[prop(optional, into)] align: OptionalMaybeSignal<SpaceAlign>,
-    #[prop(optional, into)] justify: OptionalMaybeSignal<SpaceJustify>,
+    #[prop(optional, into)] align: MaybeProp<SpaceAlign>,
+    #[prop(optional, into)] justify: MaybeProp<SpaceJustify>,
     #[prop(optional, into)] class: MaybeProp<String>,
     children: ChildrenFragment,
 ) -> impl IntoView {
diff --git a/thaw_utils/src/optional_prop.rs b/thaw_utils/src/optional_prop.rs
index bcda1c3..ba163a1 100644
--- a/thaw_utils/src/optional_prop.rs
+++ b/thaw_utils/src/optional_prop.rs
@@ -1,4 +1,7 @@
-use leptos::prelude::{MaybeSignal, Memo, ReadSignal, RwSignal, Signal};
+use leptos::{
+    prelude::{MaybeSignal, Memo, ReadSignal, RwSignal, Signal},
+    reactive_graph::owner::Storage,
+};
 use std::ops::{Deref, DerefMut};
 
 use crate::BoxOneCallback;
@@ -58,6 +61,7 @@ impl From<&str> for OptionalProp<String> {
     }
 }
 
+/// TODO remove signal
 impl From<&str> for OptionalProp<MaybeSignal<String>> {
     fn from(value: &str) -> Self {
         Self(Some(MaybeSignal::from(value.to_string())))
@@ -88,8 +92,11 @@ impl<T: Send + Sync> From<Memo<T>> for OptionalProp<MaybeSignal<T>> {
     }
 }
 
-impl<T> From<Signal<T>> for OptionalProp<MaybeSignal<T>> {
-    fn from(value: Signal<T>) -> Self {
+impl<T, S> From<Signal<T, S>> for OptionalProp<MaybeSignal<T, S>>
+where
+    S: Storage<T>,
+{
+    fn from(value: Signal<T, S>) -> Self {
         Self(Some(MaybeSignal::from(value)))
     }
 }
diff --git a/thaw_utils/src/signals/mod.rs b/thaw_utils/src/signals/mod.rs
index a8b3364..d91f8c0 100644
--- a/thaw_utils/src/signals/mod.rs
+++ b/thaw_utils/src/signals/mod.rs
@@ -1,11 +1,9 @@
 mod component_ref;
 mod model;
-mod optional_maybe_signal;
 mod signal_watch;
 mod stored_maybe_signal;
 
 pub use component_ref::ComponentRef;
 pub use model::{Model, OptionModel, VecModel};
-pub use optional_maybe_signal::OptionalMaybeSignal;
 pub use signal_watch::SignalWatch;
 pub use stored_maybe_signal::StoredMaybeSignal;
diff --git a/thaw_utils/src/signals/model.rs b/thaw_utils/src/signals/model.rs
index 5c8f86c..6f0b01a 100644
--- a/thaw_utils/src/signals/model.rs
+++ b/thaw_utils/src/signals/model.rs
@@ -6,18 +6,20 @@ pub use vec_model::VecModel;
 
 use leptos::reactive_graph::{
     computed::Memo,
+    owner::{Storage, SyncStorage},
     signal::{ReadSignal, RwSignal, WriteSignal},
     traits::{DefinedAt, IsDisposed, Set, Update, With, WithUntracked},
     wrappers::read::Signal,
 };
 
-pub struct Model<T>
+pub struct Model<T, S = SyncStorage>
 where
     T: 'static,
+    S: Storage<T>,
 {
-    read: Signal<T>,
-    write: WriteSignal<T>,
-    on_write: Option<WriteSignal<T>>,
+    read: Signal<T, S>,
+    write: WriteSignal<T, S>,
+    on_write: Option<WriteSignal<T, S>>,
 }
 
 impl<T: Default + Send + Sync> Default for Model<T> {
@@ -26,13 +28,16 @@ impl<T: Default + Send + Sync> Default for Model<T> {
     }
 }
 
-impl<T> Clone for Model<T> {
+impl<T, S> Clone for Model<T, S>
+where
+    S: Storage<T>,
+{
     fn clone(&self) -> Self {
         *self
     }
 }
 
-impl<T> Copy for Model<T> {}
+impl<T, S> Copy for Model<T, S> where S: Storage<T> {}
 
 impl<T: Send + Sync> Model<T> {
     fn new(value: T) -> Self {
@@ -45,9 +50,12 @@ impl<T: Send + Sync> Model<T> {
     }
 }
 
-impl<T> DefinedAt for Model<T> {
+impl<T, S> DefinedAt for Model<T, S>
+where
+    S: Storage<T>,
+{
     fn defined_at(&self) -> Option<&'static std::panic::Location<'static>> {
-        todo!()
+        self.read.defined_at()
     }
 }
 
@@ -82,7 +90,10 @@ impl<T: Send + Sync + Clone> Update for Model<T> {
     }
 }
 
-impl<T> IsDisposed for Model<T> {
+impl<T, S> IsDisposed for Model<T, S>
+where
+    S: Storage<T>,
+{
     fn is_disposed(&self) -> bool {
         self.write.is_disposed()
     }
@@ -105,8 +116,11 @@ impl<T: Send + Sync> From<RwSignal<T>> for Model<T> {
     }
 }
 
-impl<T> From<(Signal<T>, WriteSignal<T>)> for Model<T> {
-    fn from((read, write): (Signal<T>, WriteSignal<T>)) -> Self {
+impl<T, S> From<(Signal<T, S>, WriteSignal<T, S>)> for Model<T, S>
+where
+    S: Storage<T>,
+{
+    fn from((read, write): (Signal<T, S>, WriteSignal<T, S>)) -> Self {
         Self {
             read,
             write,
diff --git a/thaw_utils/src/signals/model/option_model.rs b/thaw_utils/src/signals/model/option_model.rs
index 618d41a..37bb30b 100644
--- a/thaw_utils/src/signals/model/option_model.rs
+++ b/thaw_utils/src/signals/model/option_model.rs
@@ -1,19 +1,21 @@
 use leptos::reactive_graph::{
     computed::Memo,
+    owner::{Storage, SyncStorage},
     signal::{ReadSignal, RwSignal, WriteSignal},
     traits::{Get, GetUntracked, Set, With, WithUntracked},
     wrappers::read::Signal,
 };
 
-pub enum OptionModel<T>
+pub enum OptionModel<T, S = SyncStorage>
 where
     T: 'static,
+    S: Storage<T> + Storage<Option<T>>,
 {
-    T(Signal<T>, WriteSignal<T>, Option<WriteSignal<T>>),
+    T(Signal<T, S>, WriteSignal<T, S>, Option<WriteSignal<T, S>>),
     Option(
-        Signal<Option<T>>,
-        WriteSignal<Option<T>>,
-        Option<WriteSignal<Option<T>>>,
+        Signal<Option<T>, S>,
+        WriteSignal<Option<T>, S>,
+        Option<WriteSignal<Option<T>, S>>,
     ),
 }
 
@@ -23,13 +25,16 @@ impl<T: Default + Send + Sync> Default for OptionModel<T> {
     }
 }
 
-impl<T> Clone for OptionModel<T> {
+impl<T, S> Clone for OptionModel<T, S>
+where
+    S: Storage<T> + Storage<Option<T>>,
+{
     fn clone(&self) -> Self {
         *self
     }
 }
 
-impl<T> Copy for OptionModel<T> {}
+impl<T, S> Copy for OptionModel<T, S> where S: Storage<T> + Storage<Option<T>> {}
 
 impl<T: Send + Sync> OptionModel<T> {
     fn new(value: T) -> Self {
@@ -112,14 +117,20 @@ impl<T: Send + Sync> From<RwSignal<Option<T>>> for OptionModel<T> {
     }
 }
 
-impl<T> From<(Signal<T>, WriteSignal<T>)> for OptionModel<T> {
-    fn from((read, write): (Signal<T>, WriteSignal<T>)) -> Self {
+impl<T, S> From<(Signal<T, S>, WriteSignal<T, S>)> for OptionModel<T, S>
+where
+    S: Storage<T> + Storage<Option<T>>,
+{
+    fn from((read, write): (Signal<T, S>, WriteSignal<T, S>)) -> Self {
         Self::T(read, write, None)
     }
 }
 
-impl<T> From<(Signal<Option<T>>, WriteSignal<Option<T>>)> for OptionModel<T> {
-    fn from((read, write): (Signal<Option<T>>, WriteSignal<Option<T>>)) -> Self {
+impl<T, S> From<(Signal<Option<T>, S>, WriteSignal<Option<T>, S>)> for OptionModel<T, S>
+where
+    S: Storage<T> + Storage<Option<T>>,
+{
+    fn from((read, write): (Signal<Option<T>, S>, WriteSignal<Option<T>, S>)) -> Self {
         Self::Option(read, write, None)
     }
 }
diff --git a/thaw_utils/src/signals/model/vec_model.rs b/thaw_utils/src/signals/model/vec_model.rs
index d6ab1b8..37f3ffc 100644
--- a/thaw_utils/src/signals/model/vec_model.rs
+++ b/thaw_utils/src/signals/model/vec_model.rs
@@ -2,26 +2,28 @@ use leptos::{
     prelude::Update,
     reactive_graph::{
         computed::Memo,
+        owner::{Storage, SyncStorage},
         signal::{ReadSignal, RwSignal, WriteSignal},
         traits::{GetUntracked, Set, With, WithUntracked},
         wrappers::read::Signal,
     },
 };
 
-pub enum VecModel<T>
+pub enum VecModel<T, S = SyncStorage>
 where
     T: 'static,
+    S: Storage<T> + Storage<Option<T>> + Storage<Vec<T>>,
 {
-    T(Signal<T>, WriteSignal<T>, Option<WriteSignal<T>>),
+    T(Signal<T, S>, WriteSignal<T, S>, Option<WriteSignal<T, S>>),
     Option(
-        Signal<Option<T>>,
-        WriteSignal<Option<T>>,
-        Option<WriteSignal<Option<T>>>,
+        Signal<Option<T>, S>,
+        WriteSignal<Option<T>, S>,
+        Option<WriteSignal<Option<T>, S>>,
     ),
     Vec(
-        Signal<Vec<T>>,
-        WriteSignal<Vec<T>>,
-        Option<WriteSignal<Vec<T>>>,
+        Signal<Vec<T>, S>,
+        WriteSignal<Vec<T>, S>,
+        Option<WriteSignal<Vec<T>, S>>,
     ),
 }
 
@@ -31,13 +33,16 @@ impl<T: Default + Send + Sync> Default for VecModel<T> {
     }
 }
 
-impl<T> Clone for VecModel<T> {
+impl<T, S> Clone for VecModel<T, S>
+where
+    S: Storage<T> + Storage<Option<T>> + Storage<Vec<T>>,
+{
     fn clone(&self) -> Self {
         *self
     }
 }
 
-impl<T> Copy for VecModel<T> {}
+impl<T, S> Copy for VecModel<T, S> where S: Storage<T> + Storage<Option<T>> + Storage<Vec<T>> {}
 
 impl<T: Send + Sync> VecModel<T> {
     fn new(value: T) -> Self {
@@ -192,20 +197,29 @@ impl<T: Send + Sync> From<RwSignal<Vec<T>>> for VecModel<T> {
     }
 }
 
-impl<T> From<(Signal<T>, WriteSignal<T>)> for VecModel<T> {
-    fn from((read, write): (Signal<T>, WriteSignal<T>)) -> Self {
+impl<T, S> From<(Signal<T, S>, WriteSignal<T, S>)> for VecModel<T, S>
+where
+    S: Storage<T> + Storage<Option<T>> + Storage<Vec<T>>,
+{
+    fn from((read, write): (Signal<T, S>, WriteSignal<T, S>)) -> Self {
         Self::T(read, write, None)
     }
 }
 
-impl<T> From<(Signal<Option<T>>, WriteSignal<Option<T>>)> for VecModel<T> {
-    fn from((read, write): (Signal<Option<T>>, WriteSignal<Option<T>>)) -> Self {
+impl<T, S> From<(Signal<Option<T>, S>, WriteSignal<Option<T>, S>)> for VecModel<T, S>
+where
+    S: Storage<T> + Storage<Option<T>> + Storage<Vec<T>>,
+{
+    fn from((read, write): (Signal<Option<T>, S>, WriteSignal<Option<T>, S>)) -> Self {
         Self::Option(read, write, None)
     }
 }
 
-impl<T> From<(Signal<Vec<T>>, WriteSignal<Vec<T>>)> for VecModel<T> {
-    fn from((read, write): (Signal<Vec<T>>, WriteSignal<Vec<T>>)) -> Self {
+impl<T, S> From<(Signal<Vec<T>, S>, WriteSignal<Vec<T>, S>)> for VecModel<T, S>
+where
+    S: Storage<T> + Storage<Option<T>> + Storage<Vec<T>>,
+{
+    fn from((read, write): (Signal<Vec<T>, S>, WriteSignal<Vec<T>, S>)) -> Self {
         Self::Vec(read, write, None)
     }
 }
diff --git a/thaw_utils/src/signals/optional_maybe_signal.rs b/thaw_utils/src/signals/optional_maybe_signal.rs
deleted file mode 100644
index d43b3be..0000000
--- a/thaw_utils/src/signals/optional_maybe_signal.rs
+++ /dev/null
@@ -1,86 +0,0 @@
-use leptos::prelude::*;
-use std::ops::Deref;
-
-pub struct OptionalMaybeSignal<T: 'static>(MaybeSignal<Option<T>>);
-
-impl<T> Default for OptionalMaybeSignal<T> {
-    fn default() -> Self {
-        Self(MaybeSignal::Static(None))
-    }
-}
-
-impl<T: Copy> Copy for OptionalMaybeSignal<T> {}
-
-impl<T: Clone> Clone for OptionalMaybeSignal<T> {
-    fn clone(&self) -> Self {
-        Self(self.0.clone())
-    }
-}
-
-impl<T> Deref for OptionalMaybeSignal<T> {
-    type Target = MaybeSignal<Option<T>>;
-
-    fn deref(&self) -> &Self::Target {
-        &self.0
-    }
-}
-
-impl<T> From<T> for OptionalMaybeSignal<T> {
-    fn from(value: T) -> Self {
-        Self(MaybeSignal::Static(Some(value)))
-    }
-}
-
-impl<T> From<Option<T>> for OptionalMaybeSignal<T> {
-    fn from(value: Option<T>) -> Self {
-        Self(MaybeSignal::Static(value))
-    }
-}
-
-impl<T: Send + Sync> From<ReadSignal<Option<T>>> for OptionalMaybeSignal<T> {
-    fn from(value: ReadSignal<Option<T>>) -> Self {
-        Self(MaybeSignal::Dynamic(value.into()))
-    }
-}
-
-impl<T: Send + Sync> From<RwSignal<Option<T>>> for OptionalMaybeSignal<T> {
-    fn from(value: RwSignal<Option<T>>) -> Self {
-        Self(MaybeSignal::Dynamic(value.into()))
-    }
-}
-
-impl<T: Send + Sync> From<Memo<Option<T>>> for OptionalMaybeSignal<T> {
-    fn from(value: Memo<Option<T>>) -> Self {
-        Self(MaybeSignal::Dynamic(value.into()))
-    }
-}
-
-impl<T> From<Signal<Option<T>>> for OptionalMaybeSignal<T> {
-    fn from(value: Signal<Option<T>>) -> Self {
-        Self(MaybeSignal::Dynamic(value))
-    }
-}
-
-impl<T> From<MaybeSignal<Option<T>>> for OptionalMaybeSignal<T> {
-    fn from(value: MaybeSignal<Option<T>>) -> Self {
-        Self(value)
-    }
-}
-
-// TODO
-// #[cfg(test)]
-// mod test {
-//     use super::OptionalMaybeSignal;
-//     use leptos::{create_runtime, MaybeSignal};
-
-//     #[test]
-//     fn into() {
-//         let runtime = create_runtime();
-
-//         let _: MaybeSignal<i32> = 12.into();
-//         let _: OptionalMaybeSignal<i32> = Some(12).into();
-//         let _: OptionalMaybeSignal<i32> = MaybeSignal::Static(Some(12)).into();
-
-//         runtime.dispose();
-//     }
-// }
diff --git a/thaw_utils/src/signals/stored_maybe_signal.rs b/thaw_utils/src/signals/stored_maybe_signal.rs
index b191509..bf5f810 100644
--- a/thaw_utils/src/signals/stored_maybe_signal.rs
+++ b/thaw_utils/src/signals/stored_maybe_signal.rs
@@ -1,21 +1,36 @@
 use leptos::reactive_graph::{
-    owner::StoredValue,
+    owner::{Storage, StoredValue, SyncStorage},
     traits::{DefinedAt, With, WithUntracked},
     wrappers::read::{MaybeSignal, Signal},
 };
 
-#[derive(Clone)]
-pub enum StoredMaybeSignal<T>
+pub enum StoredMaybeSignal<T, S = SyncStorage>
 where
     T: 'static,
+    S: Storage<T>,
 {
-    StoredValue(StoredValue<T>),
-    Signal(Signal<T>),
+    StoredValue(StoredValue<T, S>),
+    Signal(Signal<T, S>),
 }
 
-impl<T: Clone> Copy for StoredMaybeSignal<T> {}
+impl<T, S> Clone for StoredMaybeSignal<T, S>
+where
+    S: Storage<T>,
+{
+    fn clone(&self) -> Self {
+        match self {
+            Self::StoredValue(v) => Self::StoredValue(v.clone()),
+            Self::Signal(s) => Self::Signal(s.clone()),
+        }
+    }
+}
 
-impl<T> DefinedAt for StoredMaybeSignal<T> {
+impl<T: Clone, S> Copy for StoredMaybeSignal<T, S> where S: Storage<T> {}
+
+impl<T, S> DefinedAt for StoredMaybeSignal<T, S>
+where
+    S: Storage<T>,
+{
     fn defined_at(&self) -> Option<&'static std::panic::Location<'static>> {
         match self {
             StoredMaybeSignal::StoredValue(value) => value.defined_at(),