code: def forward_and_backward(self):
      self.zero_losses()
      self.zero_grad()
      self.update_loss_weights()
      self.calculate_loss(self.get_batch())
      self.loss_tracker.update(self.loss_weights)
      self.backward()
      self.clip_gradients()
      self.step_optimizers()
  
imports: import torch
  import tqdm
  from ..utils import common_functions
  from ..utils import loss_tracker
  from ..utils.key_checker import KeyChecker, KeyCheckerDict
label_desc: Use image node_id 7 for calling the BaseTrainer obj's underlying member method code with example usage: obj.forward_and_backward() without return types