class_docstr: `AgentBase` is the base class of the `parl.Agent` in different frameworks.
  
  `parl.Agent` is responsible for the general data flow outside the algorithm.
docstr: The training interface for Agent.
  
  This function will usually do the following things:
      1. Accept numpy data as input;
      2. Feed numpy data or onvert numpy data to tensor (optional);
      3. Call learn function in `Algorithm`.
code: def learn(self, *args, **kwargs):
      """The training interface for Agent.
  
      This function will usually do the following things:
          1. Accept numpy data as input;
          2. Feed numpy data or onvert numpy data to tensor (optional);
          3. Call learn function in `Algorithm`.
      """
      raise NotImplementedError
  
file_path: PARL/parl/core/agent_base.py
label_desc: Use image node_id 4 for calling the AgentBase obj's underlying member method code with example usage: obj.learn() without return types