code: def forward(self, x):
      sample = x
      sample = self.conv_in(sample)
  
      # down
      for down_block in self.down_blocks:
          sample = down_block(sample)
  
      # middle
      sample = self.mid_block(sample)
  
      # post-process
      sample = self.conv_norm_out(sample)
      sample = self.conv_act(sample)
      sample = self.conv_out(sample)
  
      return sample
  
imports: import numpy
  import paddle
  import paddle.nn
  from ..configuration_utils import ConfigMixin
  from ..configuration_utils import register_to_config
  from .unet_blocks import get_down_block
  from .unet_blocks import get_up_block
  from .unet_blocks import UNetMidBlock2D
label_desc: Use image node_id 2 for calling the Encoder obj's underlying member method code with example usage: obj.forward(x) and returns: sample