old_contents: import os
  import urllib
  
  # This script downloads these .mag files if not already present.
  mag_files = [
      'http://download.magenta.tensorflow.org/models/attention_rnn.mag',
      'http://download.magenta.tensorflow.org/models/performance.mag',
      'http://download.magenta.tensorflow.org/models/pianoroll_rnn_nade.mag',
      'http://download.magenta.tensorflow.org/models/drum_kit_rnn.mag',
  ]
  
  for mag_file in mag_files:
    output_file = mag_file.split('/')[-1]
    if os.path.exists(output_file):
      print 'File %s already present' % mag_file
    else:
      print 'Writing %s to %s' % (mag_file, output_file)
      urlopener = urllib.URLopener()
      urlopener.retrieve(mag_file, output_file)
  
new_contents: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  
  import os
  from six.moves.urllib.request import URLopener
  
  # This script downloads these .mag files if not already present.
  mag_files = [
      'http://download.magenta.tensorflow.org/models/attention_rnn.mag',
      'http://download.magenta.tensorflow.org/models/performance.mag',
      'http://download.magenta.tensorflow.org/models/pianoroll_rnn_nade.mag',
      'http://download.magenta.tensorflow.org/models/drum_kit_rnn.mag',
  ]
  
  for mag_file in mag_files:
    output_file = mag_file.split('/')[-1]
    if os.path.exists(output_file):
      print('File %s already present' % mag_file)
    else:
      print('Writing %s to %s' % (mag_file, output_file))
      urlopener = URLopener()
      urlopener.retrieve(mag_file, output_file)
  
subject: Use print() function in both Python 2 and Python 3 (#52)