code: def forward(self, x):
      B, C, H, W = x.shape
      # reshape
      x = x.reshape([B, C, -1]).transpose([0, 2, 1])
      # Attention
      x = x + self.drop_path(self.attn(self.norm1(x), H, W))
      # FFN
      x = x + self.drop_path(self.mlp(self.norm2(x), H, W))
      # reshape
      x = x.transpose([0, 2, 1]).reshape([B, C, H, W])
      return x
  
imports: import paddle
  import paddle.nn
  import paddle.nn.functional
  from paddleseg.cvlibs import manager, param_init
  from paddleseg.models import layers
  from paddleseg.utils import utils, logger
  from paddleseg.models.backbones.transformer_utils import *
label_desc: Use image node_id 2 for calling the GeneralTransformerBlock obj's underlying member method code with example usage: obj.forward(x) and returns: x