code: def setUp(self):
      super().setUp()
      torch.set_rng_state(torch.manual_seed(42).get_state())
  
      self.batch_size = 4
      self.seq_len = 16
      self.feature_dim = 8
      self.fake_input = torch.randn(
          (self.batch_size, self.seq_len, self.feature_dim)
      ).float()
      lengths = torch.Tensor([16, 0, 14, 15, 16, 16, 16, 16])
      self.mask = torch.lt(
          torch.arange(self.seq_len)[None, :], lengths[:, None].long()
      )
  
file_path: pytorchvideo/tests/test_layers_positional_encoding.py
imports: import itertools
  import math
  import unittest
  import torch
  from pytorchvideo.layers import PositionalEncoding, SpatioTemporalClsPositionalEncoding
label_desc: Use image node_id 1 for calling the TestPositionalEncoding obj's underlying member method code with example usage: obj.setUp() without return types