code: def __init__(
      self,
      in_channels: int,
      num_classes: Optional[int] = None,
      *,
      num_layers: int = 2,
      start_channels: int = 16,
      norm_type: Optional[str] = "batch",
  ):
      super().__init__(in_channels, num_classes)
      self.num_layers = num_layers
      self.start_channels = start_channels
      # backbone
      blocks: List[nn.Module] = [
          Conv2d(
              in_channels,
              self.start_channels,
              kernel_size=4,
              stride=2,
              padding=1,
              bias=True,
          ),
          nn.LeakyReLU(0.2, inplace=True),
      ]
      use_bias = norm_type != "batch"
      nc_multiplier = 1
      for i in range(1, num_layers):
          nc_multiplier_prev = nc_multiplier
          nc_multiplier = min(2**i, 8)
          blocks.extend(
              get_conv_blocks(
                  start_channels * nc_multiplier_prev,
                  start_channels * nc_multiplier,
                  4,
                  1 if i == num_layers - 1 else 2,
                  bias=use_bias,
                  padding=1,
                  norm_type=norm_type,
                  activation=nn.LeakyReLU(0.2, inplace=True),
              )
          )
      self.net = nn.Sequential(*blocks)
      # heads
      out_channels = start_channels * nc_multiplier
      self.clf = Conv2d(
          out_channels,
          1,
          kernel_size=4,
          padding=1,
          stride=1,
          bias=True,
      )
      # conditional
      self.generate_cond(out_channels)
      # initialize
      self.apply(weights_init)
  
imports: import torch
  import torch.nn
  from typing import Any
  from typing import Dict
  from typing import List
  from typing import Type
  from typing import Optional
  from cftool.misc import WithRegister
  from ....losses.gan import DiscriminatorOutput
  from ....modules.blocks import get_conv_blocks
  from ....modules.blocks import Conv2d
label_desc: Use image node_id 1 to create a new NLayerDiscriminator object from inherited base classes: DiscriminatorBase with example: obj = NLayerDiscriminator(in_channels, num_classes)