class_docstr: Combination of multiple reward.
code: def reward(self, simulator_state: Any) -> float:
      total_reward = 0.0
      for name, (reward_fn, weight) in self.rewards.items():
          rew = reward_fn(simulator_state) * weight
          total_reward += rew
          self.log(name, rew)
      return total_reward
  
file_path: qlib/qlib/rl/reward.py
imports: from __future__ import annotations
  from typing import TYPE_CHECKING, Any, Dict, Generic, Optional, Tuple, TypeVar
  from qlib.typehint import final
label_desc: Use image node_id 2 for calling the RewardCombination obj's underlying member method code with example usage: obj.reward(simulator_state) and returns: total_reward