code: def forward(self, x):
      identity = x
      out = self.layers(x)
      if not self.add_identity:
          return out
      else:
          return out + identity
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import copy
  import paddle
  from paddle import nn
  from ppdet.core.workspace import register
  from ppdet.modeling import initializer
  from .roi_extractor import RoIAlign
  from ..bbox_utils import delta2bbox_v2
  from ..cls_utils import _get_class_default_kwargs
  from ..layers import MultiHeadAttention
label_desc: Use image node_id 2 for calling the FFN obj's underlying member method code with example usage: obj.forward(x) and returns: out, unknown