class_docstr: A test for focal loss.
class_docstr_tok: ["A","test","for","focal","loss","."]
code: def setUp(self):
      x = torch.rand(128, 1000, 8, 4) * random.randint(1, 10)
      self.input = Variable(x)
      l = torch.rand(128, 8, 4) * 1000  # 1000 is classes_num
      l = l.long()
      self.target = Variable(l)
  
file_path: towhee/tests/unittests/models/loss/test_focal_loss.py
imports: import unittest
  import random
  import torch
  import torch.nn.functional
  from torch.autograd import Variable
  from torch import nn
  from towhee.models.loss.focal_loss import FocalLoss
label_desc: Use image node_id 1 for calling the TestOperator obj's underlying member method code with example usage: obj.setUp() without return types