docstr: return a instance of User() represents a user to be processed
      Parameter
          user_id : string
      :return
          user : User()
docstr_tok: ["return","a","instance","of","User","(",")","represents","a","user","to","be","processed","Parameter","user_id",":","string",":","return","user",":","User","(",")"]
code: def load_user(self, user_id):
      """
      return a instance of User() represents a user to be processed
          Parameter
              user_id : string
          :return
              user : User()
      """
      account_path = self.data_path / user_id
      strategy_file = (
          self.data_path
          / user_id
          / "strategy_{}.pickle".format(user_id)
      )
      model_file = (
          self.data_path / user_id / "model_{}.pickle".format(user_id)
      )
      cur_user_list = list(self.users)
      if user_id in cur_user_list:
          raise ValueError("User {} has been loaded".format(user_id))
      else:
          trade_account = Account(0)
          trade_account.load_account(account_path)
          strategy = load_instance(strategy_file)
          model = load_instance(model_file)
          user = User(
              account=trade_account, strategy=strategy, model=model
          )
          return user
  
file_path: qlib/qlib/contrib/online/manager.py
imports: import yaml
  import pathlib
  import pandas
  import shutil
  from ...backtest.account import Account
  from .user import User
  from .utils import load_instance, save_instance
  from ...utils import init_instance_by_config
label_desc: Use image node_id 3 for calling the UserManager obj's underlying member method code with example usage: obj.load_user(user_id) and returns: user