class_docstr: ClassAttention
class_docstr_tok: ["ClassAttention"]
code: def forward(self, x):
      b, n, _ = x.shape
      kv = (
          self.kv(x)
          .reshape(b, n, 2, self.num_heads, self.head_dim)
          .permute(2, 0, 3, 1, 4)
      )
      k, v = kv[0], kv[1]
      q = self.q(x[:, :1, :]).reshape(
          b, self.num_heads, 1, self.head_dim
      )
      attn = (q * self.scale) @ k.transpose(-2, -1)
      attn = attn.softmax(dim=-1)
      cls_embed = (
          (attn @ v)
          .transpose(1, 2)
          .reshape(b, 1, self.head_dim * self.num_heads)
      )
      cls_embed = self.proj(cls_embed)
      return cls_embed
  
imports: import torch
  from torch import nn
  from timm.models.layers import DropPath
  import numpy
  from towhee.models.wave_vit.wave_vit_utils import DWT2D, IDWT2D
  from towhee.models.utils.init_vit_weights import init_vit_weights
  from towhee.models.layers.mlp import Mlp
label_desc: Use image node_id 2 for calling the ClassAttention obj's underlying member method code with example usage: obj.forward(x) and returns: cls_embed