message: Add Freeze for Box
  Summary: Useful to have.
diff: @@ -122,6 +122,17 @@ where
  }
  }
  +impl<T> Freeze for Box<T>
  +where
  + T: Freeze,
  +{
  + type Frozen = Box<T::Frozen>;
  +
  + fn freeze(self, freezer: &Freezer) -> anyhow::Result<Self::Frozen> {
  + Ok(box (*self).freeze(freezer)?)
  + }
  +}
  +
  impl<T> Freeze for Option<T>
  where
  T: Freeze,
  