Wrap class as PyTree

Needed to make the `autolens.Tracer` example work.

autoarray/operators/over_sampling/uniform.py

@@ -14,7 +14,10 @@
 from autoarray import exc
 from autoarray.operators.over_sampling import over_sample_util
 
+from autofit.jax_wrapper import register_pytree_node_class
 
+
+@register_pytree_node_class
 class OverSamplingUniform(AbstractOverSampling):
     def __init__(self, sub_size: Union[int, Array2D]):
         """
@@ -319,6 +322,15 @@ def over_sampler_from(self, mask: Mask2D) -> "OverSamplerUniform":
             mask=mask,
             sub_size=self.sub_size,
         )
+
+    def tree_flatten(self):
+        children = (self.sub_size,)
+        aux_data = None
+        return (children, aux_data)
+
+    @classmethod
+    def tree_unflatten(cls, aux_data, children):
+        return cls(*children)
 
 
 class OverSamplerUniform(AbstractOverSampler):