old_contents: import unittest
  
  from crossword import Crossword
  
  
  class CrosswordTestCase(unittest.TestCase):
  
      def test_crossword_set_and_get_element(self):
          c = Crossword(10, 10)
          c[3, 3] = 'A'
          self.assertEqual(c[3, 3], 'A')
  
new_contents: import unittest
  
  from crossword import Crossword
  
  
  class CrosswordTestCase(unittest.TestCase):
  
      def test_crossword_set_and_get_element(self):
          crossword = Crossword(10, 10)
          crossword[3, 3] = 'A'
          self.assertEqual(crossword[3, 3], 'A')
  
subject: Use a better variable name instead of one character