code: def _select_block(block_type):
      if block_type == NBeatsNet.SEASONALITY_BLOCK:
          return SeasonalityBlock
      elif block_type == NBeatsNet.TREND_BLOCK:
          return TrendBlock
      else:
          return GenericBlock
  
imports: import pickle
  import random
  from time import time
  from typing import Union
  import numpy
  import torch
  from torch import nn, optim
  from torch.nn import functional
  from torch.nn.functional import mse_loss, l1_loss, binary_cross_entropy, cross_entropy
  from torch.optim import Optimizer
  from .utils import PYTORCH_REGRESSION_LOSS_MAP
  from pytorch_lightning import seed_everything
label_desc: Use image node_id 3 for calling the NBeatsNet obj's underlying member method code with example usage: obj._select_block(block_type) and returns: SeasonalityBlock, TrendBlock, GenericBlock