code: def create(cls, group, admin):
          
          with db.session.begin_nested():
              obj = cls(
                  group=group,
                  admin=admin,
              )
              db.session.add(obj)
          return obj
docs: Create a new group admin.
  
          :param group: Group object.
          :param admin: Admin object.
          :returns: Newly created GroupAdmin object.
          :raises: IntegrityError