code: def test_square(self):
      # Multiplication makes a special case of multiplying an int with
      # itself, using a special, faster algorithm. This test is mostly
      # to ensure that no asserts in the implementation trigger, in
      # cases with a maximal amount of carries.
      for bitlen in range(1, 400):
          n = (1 << bitlen) - 1  # solid string of 1 bits
          with self.subTest(bitlen=bitlen, n=n):
              # (2**i - 1)**2 = 2**(2*i) - 2*2**i + 1
              self.assertEqual(
                  n**2, (1 << (2 * bitlen)) - (1 << (bitlen + 1)) + 1
              )
  
imports: import unittest
  from test import support
  import sys
  import random
  import math
  import array
label_desc: Use image node_id 53 for calling the LongTest obj's underlying member method code with example usage: obj.test_square() without return types