code: def forward(self, x, identity=None):
      out = self.layers(x)
      if not self.add_identity:
          return self.dropout_layer(out)
      if identity is None:
          identity = x
      return identity + self.dropout_layer(out)
  
imports: import paddle
  import paddle.nn
  import paddle.nn.functional
  from paddleseg import utils
  from paddleseg.cvlibs import manager
  from paddleseg.models import layers
  from .upernet import UPerNetHead
label_desc: Use image node_id 2 for calling the FFN obj's underlying member method code with example usage: obj.forward(x, identity) and returns: unknown, self