code: def forward(
      self,
      tgt,
      reference_points,
      memory,
      memory_spatial_shapes,
      memory_level_start_index,
      attn_mask=None,
      memory_mask=None,
      query_pos_embed=None,
  ):
      # self attention
      q = k = self.with_pos_embed(tgt, query_pos_embed)
      if attn_mask is not None:
          attn_mask = paddle.where(
              attn_mask.astype("bool"),
              paddle.zeros(attn_mask.shape, tgt.dtype),
              paddle.full(attn_mask.shape, float("-inf"), tgt.dtype),
          )
      tgt2 = self.self_attn(q, k, value=tgt, attn_mask=attn_mask)
      tgt = tgt + self.dropout1(tgt2)
      tgt = self.norm1(tgt)
  
      # cross attention
      tgt2 = self.cross_attn(
          self.with_pos_embed(tgt, query_pos_embed),
          reference_points,
          memory,
          memory_spatial_shapes,
          memory_level_start_index,
          memory_mask,
      )
      tgt = tgt + self.dropout2(tgt2)
      tgt = self.norm2(tgt)
  
      # ffn
      tgt2 = self.forward_ffn(tgt)
      tgt = tgt + self.dropout4(tgt2)
      tgt = self.norm3(tgt)
  
      return tgt
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import paddle
  import paddle.nn
  import paddle.nn.functional
  from paddle import ParamAttr
  from paddle.regularizer import L2Decay
  from ppdet.core.workspace import register
  from ..layers import MultiHeadAttention
  from ..heads.detr_head import MLP
  from .deformable_transformer import MSDeformableAttention
  from ..initializer import linear_init_, constant_, xavier_uniform_, normal_, bias_init_with_prob
  from .utils import _get_clones, get_sine_pos_embed, get_contrastive_denoising_training_group, inverse_sigmoid
label_desc: Use image node_id 5 for calling the TransformerDecoderLayer obj's underlying member method code with example usage: obj.forward(tgt, reference_points, memory, memory_spatial_shapes, memory_level_start_index, attn_mask, memory_mask, query_pos_embed) and returns: tgt