new_contents: import __builtin__
  import os
  import sys
  
  from pyflakes.scripts.pyflakes import main
  
  """
   wrapper for pyflakes to ignore gettext based warning:
       "undefined name '_'"
  
   From https://bugs.launchpad.net/pyflakes/+bug/844592
  """
  
  names = os.environ.get('PYFLAKES_BUILTINS', '_')
  names = [x.strip() for x in names.split(',')]
  for x in names:
      if not hasattr(__builtin__, x):
          setattr(__builtin__, x, True)
  
  del names, os, __builtin__
  
  sys.exit(main())
  
subject: Add pyflakes option to tox