code: def forward(self, x):
      c1 = self.stem(x)
      c2 = self.conv2(c1)
      c3 = self.conv3(c2)
      c4 = self.conv4(c3)
      c1 = self.fc1(c1)
      c2 = self.fc2(c2)
      c3 = self.fc3(c3)
      c4 = self.fc4(c4)
  
      bs, dim, _, _ = c1.shape
      c2 = c2.reshape([bs, dim, -1]).transpose([0, 2, 1])  # 8s
      c3 = c3.reshape([bs, dim, -1]).transpose([0, 2, 1])  # 16s
      c4 = c4.reshape([bs, dim, -1]).transpose([0, 2, 1])  # 32s
  
      return c1, c2, c3, c4
  
imports: import math
  import warnings
  from functools import partial
  import paddle
  import paddle.nn
  import paddle.nn.functional
  from paddleseg.models.backbones.transformer_utils import DropPath
  from paddleseg.models.layers.ms_deformable_attention import MSDeformAttn
label_desc: Use image node_id 2 for calling the SpatialPriorModule obj's underlying member method code with example usage: obj.forward(x) and returns: c1,  c2,  c3,  c4