code: def forward(self, tgt, memory=None, self_mask=None, cross_mask=None):
      if self.with_self_attn:
          tgt1 = self.self_attn(tgt, attn_mask=self_mask)
          tgt = self.norm1(tgt + self.dropout1(tgt1))
  
      if self.with_cross_attn:
          tgt2 = self.cross_attn(tgt, key=memory, attn_mask=cross_mask)
          tgt = self.norm2(tgt + self.dropout2(tgt2))
      tgt = self.norm3(tgt + self.dropout3(self.mlp(tgt)))
      return tgt
  
imports: import math
  import paddle
  from paddle import nn
  import paddle.nn.functional
  from paddle.nn import LayerList
  from paddle.nn import Dropout, Linear, LayerNorm
  import numpy
  from ppocr.modeling.backbones.rec_svtrnet import Mlp, zeros_, ones_
  from paddle.nn.initializer import XavierNormal
label_desc: Use image node_id 2 for calling the TransformerBlock obj's underlying member method code with example usage: obj.forward(tgt, memory, _mask, cross_mask) and returns: tgt