message: ListRef::from_frozen_value
  Summary: Following diff removes `FrozenList` from public API.
diff: @@ -27,6 +27,7 @@ use crate::values::list::FrozenList;
  use crate::values::list::List;
  use crate::values::type_repr::StarlarkTypeRepr;
  use crate::values::Coerce;
  +use crate::values::FrozenValue;
  use crate::values::UnpackValue;
  use crate::values::Value;
  use crate::values::ValueLike;
  @@ -66,6 +67,12 @@ impl<'v> ListRef<'v> {
  Some(ListRef::new(ptr.0.content()))
  }
  }
  +
  + /// Downcast the list.
  + pub fn from_frozen_value<'f>(x: FrozenValue) -> Option<&'f ListRef<'f>> {
  + x.downcast_ref::<ListGen<FrozenList>>()
  + .map(|x| ListRef::new(coerce(x.0.content())))
  + }
  }
  impl<'v> Deref for ListRef<'v> {
  