code: def create(self, rs_params):
          
          repl_id = rs_params.get('id', None)
          if repl_id is not None and repl_id in self:
              raise ReplicaSetError(
                  "replica set with id={id} already exists".format(id=repl_id))
          repl = ReplicaSet(rs_params)
          self[repl.repl_id] = repl
          return repl.repl_id
docs: create new replica set
          Args:
             rs_params - replica set configuration
          Return repl_id which can use to take the replica set