code: def forward(
      self,
      src,
      reference_points,
      spatial_shapes,
      level_start_index,
      src_mask=None,
      query_pos_embed=None,
  ):
      # self attention
      src2 = self.self_attn(
          self.with_pos_embed(src, query_pos_embed),
          reference_points,
          src,
          spatial_shapes,
          level_start_index,
          src_mask,
      )
      src = src + self.dropout1(src2)
      src = self.norm1(src)
      # ffn
      src = self.forward_ffn(src)
  
      return src
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import math
  import paddle
  import paddle.nn
  import paddle.nn.functional
  from paddle import ParamAttr
  from ppdet.core.workspace import register
  from ..layers import MultiHeadAttention
  from .position_encoding import PositionEmbedding
  from .utils import _get_clones, get_valid_ratio
  from ..initializer import linear_init_, constant_, xavier_uniform_, normal_
label_desc: Use image node_id 5 for calling the DeformableTransformerEncoderLayer obj's underlying member method code with example usage: obj.forward(src, reference_points, spatial_shapes, level_start_index, src_mask, query_pos_embed) and returns: src