code: def forward(self, style_input):
      encode_bg_output = self.encoder_bg(style_input)
      decode_bg_output = self.decoder_bg(
          encode_bg_output["res_blocks"],
          encode_bg_output["down2"],
          encode_bg_output["down1"],
      )
  
      fake_c_temp = decode_bg_output["out_conv"]
      fake_bg_mask = self.decoder_mask.forward(
          encode_bg_output["res_blocks"]
      )["out_conv"]
      fake_bg = self.middle(
          paddle.concat((fake_c_temp, fake_bg_mask), axis=1)
      )
      return {
          "bg_encode_feature": encode_bg_output["res_blocks"],
          "bg_decode_feature1": decode_bg_output["up1"],
          "bg_decode_feature2": decode_bg_output["up2"],
          "fake_bg": fake_bg,
          "fake_bg_mask": fake_bg_mask,
      }
  
imports: import paddle
  import paddle.nn
  from arch.base_module import MiddleNet, ResBlock
  from arch.encoder import Encoder
  from arch.decoder import Decoder, DecoderUnet, SingleDecoder
  from utils.load_params import load_dygraph_pretrain
  from utils.logging import get_logger
label_desc: Use image node_id 2 for calling the BgGeneratorWithMask obj's underlying member method code with example usage: obj.forward(style_input) and returns: dict