code: def __init__(self, in_channels=3):
      super().__init__()
  
      self.double_conv = nn.Sequential(
          layers.ConvBNReLU(in_channels, 64, 3),
          layers.ConvBNReLU(64, 64, 3),
      )
      down_channels = [[64, 128], [128, 256], [256, 512], [512, 512]]
      self.down_sample_list = nn.LayerList(
          [
              self.down_sampling(channel[0], channel[1])
              for channel in down_channels
          ]
      )
  
imports: import paddle
  import paddle.nn
  import paddle.nn.functional
  from paddleseg import utils
  from paddleseg.cvlibs import manager
  from paddleseg.models import layers
label_desc: Use image node_id 1 to create a new Encoder object from inherited base classes: nn with example: obj = Encoder(in_channels)