new_contents: from browser import document, html, window
  
  with open('test.html') as f:
      f.read()
  
  with open('files/text-utf8.txt') as f:
      f.read()
  
  with open('compression/du cote de chez swann.txt', 'rb') as f:
      assert len(f.read()) == 1_056_294
  
  with open('compression/du cote de chez swann.txt', 'r') as f:
      assert len(f.readlines()) == 2118
  
  with open('compression/du cote de chez swann.txt', 'r') as f:
      counter = 0
      for line in f:
          counter += 1
      assert counter == 2118
  
  try:
      with open('files/text-latin1.txt') as f:
          f.read()
      raise Exception('should have raised UnicodeDecodeError')
  except UnicodeDecodeError:
      pass
  
  with open('files/text-latin1.txt', encoding='latin1') as f:
      assert f.read() == "bébé"
  
  with open('files/text-latin9.txt', encoding='iso-8859-15') as f:
      assert f.read() == "sœur"
  
  # image file
  with open('../brython.png', 'rb') as f:
      content = f.read()
      assert isinstance(content, bytes)
      assert len(content) == 2011
  
  print("passed all tests...")
subject: Add test for file objects created by open()