old_contents: #!/usr/local/bin/python3
  # Python Challenge - 18
  # http://www.pythonchallenge.com/pc/return/balloons.html
  # http://www.pythonchallenge.com/pc/return/brightness.html
  # http://www.pythonchallenge.com/pc/return/deltas.gz
  # Username: huge; Password: file
  # Keywords: ../hex/bin.html, butter, fly
  
  import difflib
  
  
  def main():
      '''
      Hint: can you tell the difference? (side by side pics of swans, one's
          darker than the other)
      brightness -> maybe consider deltas.gz
      '''
      a, b = [], []
  
      with open('./delta_chall_18/deltas', 'rb') as deltas:
          for line in deltas.readlines():
              a.append(line[:53].decode() + '\n')
              b.append(line[56:].decode())
  
      diff = difflib.ndiff(a, b)
      # print(type(diff))  # generator
  
      d_minus = open('./delta_chall_18/d_minus.png', 'wb')
      d_plus = open('./delta_chall_18/d_plus.png', 'wb')
      d_same = open('./delta_chall_18/d_same.png', 'wb')
  
      for line in diff:
          # Convert non-+/- diff part to byte array
          byte_line = bytes([
              int(n, 16) for n in line[2:].strip().split(" ") if n])
          if line[0] == '+':
              d_plus.write(byte_line)
          elif line[0] == '-':
              d_minus.write(byte_line)
          else:
              d_same.write(byte_line)
  
      d_minus.close()
      d_plus.close()
      d_same.close()
  
      return 0
  
  
  if __name__ == '__main__':
      main()
  
new_contents: #!/usr/local/bin/python3
  # Python Challenge - 18
  # http://www.pythonchallenge.com/pc/return/balloons.html
  # http://www.pythonchallenge.com/pc/return/brightness.html
  # http://www.pythonchallenge.com/pc/return/deltas.gz
  # Username: huge; Password: file
  # Keywords: ../hex/bin.html, butter, fly
  
  import difflib
  
  
  def main():
      '''
      Hint: can you tell the difference? (side by side pics of swans, one's
          darker than the other)
      brightness -> maybe consider deltas.gz
      '''
      a, b = [], []
  
      with open('./delta_chall_18/deltas', 'rb') as deltas:
          for line in deltas.readlines():
              a.append(line[:53].decode() + '\n')
              b.append(line[56:].decode())
  
      diff = difflib.ndiff(a, b)
      # print(type(diff))  # generator
  
      d_minus = open('./delta_chall_18/d_minus.png', 'wb')
      d_plus = open('./delta_chall_18/d_plus.png', 'wb')
      d_same = open('./delta_chall_18/d_same.png', 'wb')
  
      for line in diff:
          # Convert non-+/- diff part to byte array
          byte_line = bytes([
              int(n, 16) for n in line[2:].strip().split(" ") if n])
  
          if line[0] == '+':
              d_plus.write(byte_line)
          elif line[0] == '-':
              d_minus.write(byte_line)
          else:
              d_same.write(byte_line)
  
      d_minus.close()
      d_plus.close()
      d_same.close()
  
      return 0
  
  
  if __name__ == '__main__':
      main()
  
subject: Add whitespace for clarity