new_contents: from __future__ import print_function
  import os
  import re
  import sys
  
  def list_vexts():
      from vext import spec_files
      for fn in spec_files():
          print(os.path.basename(fn))
  
  def enable():
      from vext import vext_pth
      _lines = []
      with open(vext_pth, mode='r') as f:
          for line in f.readlines():
              if line.startswith('#') and line[1:].lstrip().startswith('import '):
                  _lines.append( line[1:].lstrip() )
              else:
                  _lines.append( line )
      
      try:
          os.unlink('%s.tmp' % vext_pth)
      except:
          pass
  
      with open('%s.tmp' % vext_pth, mode='w+') as f:
          f.writelines(_lines)
  
      try:
          os.unlink('%s~' % vext_pth)
      except:
          pass
  
      os.rename(vext_pth, '%s~' % vext_pth)
      os.rename('%s.tmp' % vext_pth, vext_pth)
  
  def disable():
      from vext import vext_pth
      _lines = []
      with open(vext_pth, mode='r') as f:
          for line in f.readlines():
              if not line.startswith('#') and line.startswith('import '):
                  _lines.append( '# %s' % line )
              else:
                  _lines.append( line )
  
      try:
          os.unlink('%s.tmp' % vext_pth)
      except:
          pass
      
      with open('%s.tmp' % vext_pth, mode='w+') as f:
          f.writelines(_lines)
  
      try:
          os.unlink('%s~' % vext_pth)
      except:
          pass
  
      os.rename(vext_pth, '%s~' % vext_pth)
      os.rename('%s.tmp' % vext_pth, vext_pth)
  
  def status():
      from vext import GatekeeperFinder
      if GatekeeperFinder.PATH_TRIGGER in sys.path:
          enabled_msg = 'enabled'
      else:
          enabled_msg = 'disabled'
      
      if os.environ['VIRTUAL_ENV']:
          print('Running in virtualenv [%s]' % enabled_msg)
      else:
          print('Not running in virtualenv [%s]' % enabled_msg)
  
  def main():
      import argparse
  
      parser = argparse.ArgumentParser(description='Access system python modules from virtualenv.')
      parser.add_argument('-l', '--list', dest='list', action='store_true', help='List external packages "Vext"')
      parser.add_argument('-e', '--enable', dest='enable', action='store_true', help='Disable Vext loader')
      parser.add_argument('-d', '--disable', dest='disable', action='store_true', help='Enable Vext loader')
      parser.add_argument('-s', '--status', dest='status', action='store_true', help='Show Vext status')
  
      args = parser.parse_args()
  
      if args.list:
          status()
          list_vexts()
      elif args.disable:
          disable()
      elif args.enable:
          enable()
      elif args.status:
          status()
      else:
          status()
          print()
          parser.print_help()
  
  
subject: Add commandline