code: def setUp(self):
      common_init(self)
      self.val = 4.0
      self.inv_scale = 0.5
      self.inv_scale_cuda = torch.tensor(
          [self.inv_scale], dtype=torch.float32, device="cuda"
      )
      self.overflow_buf = torch.zeros(1, dtype=torch.int, device="cuda")
  
file_path: apex/tests/L0/run_amp/test_multi_tensor_unscale_l2norm.py
imports: import unittest
  import functools
  import itertools
  from apex import amp
  import torch
  from torch import nn
  import torch.nn.functional
  from utils import common_init, HALF, FLOAT, ALWAYS_HALF, ALWAYS_FLOAT, MATCH_INPUT
label_desc: Use image node_id 1 for calling the TestMultiTensorUnscaleL2Norm obj's underlying member method code with example usage: obj.setUp() without return types