old_contents: #!/bin/python
  """
  reversebinary puzzle for Spotify.com
  
  v1
  
  Jose Antonio Navarrete
  
  You can find me at janavarretecristino@gmail.com
  Follow me on twitter @joseanavarrete
  """
  
  import unittest
  
  MAX_VALUE = 1000000000
  
  def reverse_binary(n):
      """
      Receives an integer (n), converts it to its reverse binary
      """
      if not 1 <= n <= MAX_VALUE:
          raise ValueError
      
      binary_str = bin(n)  # '0bXXXX' where XXXX is n in binary
      return int(binary_str[::-1][:-2], 2)
  
  
  class ReverseBinaryTest(unittest.TestCase):
      def test_reverse_binary(self):
          self.assertEqual(reverse_binary(1), 1)
          self.assertEqual(reverse_binary(13), 11)
          self.assertEqual(reverse_binary(47), 61)
  
      def test_wrong_input(self):
          with self.assertRaises(ValueError):
              reverse_binary(0)
              reverse_binary(MAX_VALUE)
  
  def main():
      unittest.main()
  
  if __name__ == '__main__':
      main()
  
new_contents: #!/bin/python
  """
  reversebinary puzzle for Spotify.com
  
  v1
  
  Jose Antonio Navarrete
  
  You can find me at janavarretecristino@gmail.com
  Follow me on twitter @joseanavarrete
  """
  
  import unittest
  
  MAX_VALUE = 1000000000
  
  def reverse_binary(n):
      """
      Receives an integer (n), converts it to its reverse binary
      """
      if not 1 <= n <= MAX_VALUE:
          raise ValueError
  
      binary_str = bin(n)  # '0bXXXX' where XXXX is n in binary
      return int(binary_str[::-1][:-2], 2)
  
  
  class ReverseBinaryTest(unittest.TestCase):
      def test_reverse_binary(self):
          self.assertEqual(reverse_binary(1), 1)
          self.assertEqual(reverse_binary(13), 11)
          self.assertEqual(reverse_binary(47), 61)
  
      def test_wrong_input(self):
          with self.assertRaises(ValueError):
              reverse_binary(0)
              reverse_binary(MAX_VALUE)
  
  def main():
      unittest.main()
  
  if __name__ == '__main__':
      main()
  
subject: Add breakline to better reading