code: def uuid(cls):
          
          if hasattr(cls, '__uuid_primary_key__') and cls.__uuid_primary_key__:
              return synonym('id')
          else:
              return immutable(Column(UUIDType(binary=False), default=uuid_.uuid4, unique=True, nullable=False))
docs: UUID column, or synonym to existing :attr:`id` column if that is a UUID