docstr: eval logic for an epoch
  
  :param epoch: Current epoch number
docstr_tok: ["eval","logic","for","an","epoch",":","param","epoch",":","Current","epoch","number"]
code: def _eval(self, epoch):
      """
      eval logic for an epoch
  
      :param epoch: Current epoch number
      """
      raise NotImplementedError
  
imports: import os
  import pathlib
  import shutil
  from pprint import pformat
  import anyconfig
  import paddle
  import numpy
  import random
  from paddle.jit import to_static
  from paddle.static import InputSpec
  from utils import setup_logger
label_desc: Use image node_id 5 for calling the BaseTrainer obj's underlying member method code with example usage: obj._eval(epoch) without return types