code: def get_user_switchable_roles(self):
          
          roles = []
          for rs in self.current.user.role_set:
              # rs.role != self.current.role is not True after python version 2.7.12
              if rs.role.key != self.current.role.key:
                  roles.append((rs.role.key, '%s %s' % (rs.role.unit.name,
                                                        rs.role.abstract_role.name)))
          return roles
docs: Returns user's role list except current role as a tuple
          (role.key, role.name)
  
          Returns:
              (list): list of tuples, user's role list except current role