code: def forward(self, x):
      h_ = x
      h_ = self.norm(h_)
      q = self.q(h_)
      k = self.k(h_)
      v = self.v(h_)
  
      # compute attention
      b, c, h, w = q.shape
      q = q.reshape(b, c, h * w)
      q = q.permute(0, 2, 1)
      k = k.reshape(b, c, h * w)
      w_ = torch.bmm(q, k)
      w_ = w_ * (int(c) ** (-0.5))
      w_ = F.softmax(w_, dim=2)
  
      # attend to values
      v = v.reshape(b, c, h * w)
      w_ = w_.permute(0, 2, 1)
      h_ = torch.bmm(v, w_)
      h_ = h_.reshape(b, c, h, w)
  
      h_ = self.proj_out(h_)
  
      return x + h_
  
imports: import torch
  import torch.nn
  import torch.nn.functional
  from basicsr.utils import get_root_logger
  from basicsr.utils.registry import ARCH_REGISTRY
label_desc: Use image node_id 2 for calling the AttnBlock obj's underlying member method code with example usage: obj.forward(x) and returns: unknown