∀ {α : Type u} {β : α → Type v} [inst : BEq α] [inst_1 : LawfulBEq α] {l l' : List ((a : α) × β a)} {a : α}
  {fallback : β a},
  Std.Internal.List.DistinctKeys l →
    l.Perm l' → Std.Internal.List.getValueCastD a l fallback = Std.Internal.List.getValueCastD a l' fallback