class_docstr: Test ACAR-NET heads
code: def test_acar(self):
      head = acar_net.head("acar", width=144, num_classes=10)
      out = head(self.data)
      self.assertTrue(out.shape == (1, 10))
  
imports: import unittest
  import torch
  from towhee.models import acar_net
label_desc: Use image node_id 2 for calling the TestHead obj's underlying member method code with example usage: obj.test_acar() without return types