code: def b16(n, activation, resolution=224):
      return nn.Sequential(
          Conv2d_BN(3, n // 8, 3, 2, 1, resolution=resolution),
          activation(),
          Conv2d_BN(
              n // 8, n // 4, 3, 2, 1, resolution=resolution // 2
          ),
          activation(),
          Conv2d_BN(
              n // 4, n // 2, 3, 2, 1, resolution=resolution // 4
          ),
          activation(),
          Conv2d_BN(n // 2, n, 3, 2, 1, resolution=resolution // 8),
      )
  
imports: import itertools
  import math
  import warnings
  import paddle
  import paddle.nn
  import paddle.nn.functional
  from paddle.nn.initializer import Constant
  from paddle.nn.initializer import TruncatedNormal
  from paddle.regularizer import L2Decay
  from .vision_transformer import Identity
  from .vision_transformer import ones_
  from .vision_transformer import trunc_normal_
  from .vision_transformer import zeros_
label_desc: Use image node_id 2 for calling a global function with example usage: b16(n, activation, resolution) and returns: nn