code: def window_partition(x, window_size):
      """
      Args:
          x: (B, H, W, C)
          window_size (int): window size
  
      Returns:
          windows: (num_windows*B, window_size, window_size, C)
      """
      B, H, W, C = x.shape
      x = x.reshape(
          [
              B,
              H // window_size,
              window_size,
              W // window_size,
              window_size,
              C,
          ]
      )
      windows = x.transpose([0, 1, 3, 2, 4, 5]).reshape(
          [-1, window_size, window_size, C]
      )
      return windows
  
imports: import paddle
  import paddle.nn
  import paddle.nn.functional
  import numpy
  from paddleseg.cvlibs import manager
  from paddleseg.utils import utils
  from paddleseg.models.backbones.transformer_utils import *
label_desc: Use image node_id 1 for calling a global function with example usage: window_partition(x, window_size) and returns: windows