class_docstr: KLDivLoss
code: def forward(self, logits_s, logits_t, mask=None):
      log_out_s = F.log_softmax(logits_s, axis=-1)
      out_t = F.softmax(logits_t, axis=-1)
      loss = self._kldiv(log_out_s, out_t, mask)
      return loss
  
imports: import paddle
  import paddle.nn
  import paddle.nn.functional
  from paddle.nn import L1Loss
  from paddle.nn import MSELoss
  from paddle.nn import SmoothL1Loss
label_desc: Use image node_id 3 for calling the KLDivLoss obj's underlying member method code with example usage: obj.forward(logits_s, logits_t, mask) and returns: loss