add context_key getter and setter to TimestepEncoder

src/refiners/foundationals/latent_diffusion/stable_diffusion_xl/unet.py

@@ -54,7 +54,12 @@ class TextTimeEmbedding(fl.Chain):
 
 
 class TimestepEncoder(fl.Passthrough):
-    def __init__(self, device: Device | str | None = None, dtype: DType | None = None) -> None:
+    def __init__(
+        self,
+        context_key: str = "timestep_embedding",
+        device: Device | str | None = None,
+        dtype: DType | None = None,
+    ) -> None:
         self.timestep_embedding_dim = 1280
         super().__init__(
             fl.Sum(
@@ -69,9 +74,21 @@ class TimestepEncoder(fl.Passthrough):
                 ),
                 TextTimeEmbedding(device=device, dtype=dtype),
             ),
-            fl.SetContext(context="range_adapter", key="timestep_embedding"),
+            fl.SetContext(context="range_adapter", key=context_key),
         )
 
+    @property
+    def context_key(self) -> str:
+        set_context_module = self.ensure_find(fl.SetContext)
+        assert set_context_module.context == "range_adapter"
+        return set_context_module.key
+
+    @context_key.setter
+    def context_key(self, value: str) -> None:
+        set_context_module = self.ensure_find(fl.SetContext)
+        assert set_context_module.context == "range_adapter"
+        set_context_module.key = value
+
 
 class SDXLCrossAttention(CrossAttentionBlock2d):
     def __init__(