old_contents: from into.utils import ext
  
  
  def test_ext():
      assert ext('a.py') == 'py'
      assert ext('apy') == ''
  
new_contents: from into.utils import ext
  
  
  def test_ext():
      assert ext('a.py') == 'py'
      assert ext('apy') == ''
      assert ext('myfile.csv.gz') == 'gz'
  
subject: Add test for gz