code: def forward(self):
      relative_position_bias = self.relative_position_bias_table[
          self.relative_position_index.view(-1)
      ].view(
          self.window_size[0] * self.window_size[1] + 1,
          self.window_size[0] * self.window_size[1] + 1,
          -1,
      )  # Wh*Ww,Wh*Ww,nH
      return relative_position_bias.transpose((2, 0, 1))
  
imports: import os
  import math
  import numpy
  import paddle
  import paddle.nn
  import paddle.nn.functional
  from paddle.nn.initializer import TruncatedNormal, Constant, Normal
  from paddleseg.cvlibs import manager
  from paddleseg.utils import utils, logger
  from paddleseg.models.backbones.transformer_utils import to_2tuple, DropPath, Identity
label_desc: Use image node_id 2 for calling the RelativePositionBias obj's underlying member method code with example usage: obj.forward() and returns: relative_position_bias