code: def test_calculate_gain_only_accepts_valid_nonlinearities(self):
      for n in [2, 5, 25]:
          # Generate random strings of lengths that definitely aren't supported
          random_string = "".join(
              [random.choice(string.ascii_lowercase) for i in range(n)]
          )
          with self.assertRaises(ValueError):
              init.calculate_gain(random_string)
  
imports: import random
  import unittest
  import math
  import string
  from functools import reduce
  from operator import mul
  from torch.testing._internal.common_utils import TestCase, TEST_SCIPY, skipIfNoLapack, skipIfTorchDynamo, run_tests
  import torch
  import torch.nn.init
  import torch.nn.functional
label_desc: Use image node_id 11 for calling the TestNNInit obj's underlying member method code with example usage: obj.test_calculate_gain_only_accepts_valid_nonlinearities() without return types