code: def add_members(self, new_members):
          
  
          if isinstance(new_members, string_types) or \
                  hasattr(new_members, "id"):
              warn("need to pass in a list")
              new_members = [new_members]
  
          self._members.update(new_members)
docs: Add objects to the group.
  
          Parameters
          ----------
          new_members : list
              A list of cobrapy objects to add to the group.