code: def forward(self, x) -> Tuple[torch.Tensor, torch.Tensor]:
      x = super().forward(x)
      backcast = self.theta_b_fc(x).mm(self.T_backcast)
      forecast = self.theta_f_fc(x).mm(self.T_forecast)
      return backcast, forecast
  
imports: from typing import Tuple
  import numpy
  import torch
  import torch.nn
  import torch.nn.functional
label_desc: Use image node_id 2 for calling the NBEATSTrendBlock obj's underlying member method code with example usage: obj.forward(x) and returns: backcast,  forecast