old_contents: #!/usr/bin/env python
  #
  # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
  # for details. All rights reserved. Use of this source code is governed by a
  # BSD-style license that can be found in the LICENSE file.
  #
  
  import shutil
  import sys
  import utils
  
  def Main():
    build_root = utils.GetBuildRoot(utils.GuessOS())
    print 'Deleting %s' % build_root
    if sys.platform != 'win32':
      shutil.rmtree(build_root, ignore_errors=True)
    else:
      # Intentionally ignore return value since a directory might be in use.
      subprocess.call(['rmdir', '/Q', '/S', build_root],
                      env=os.environ.copy(),
                      shell=True)
    return 0
  
  if __name__ == '__main__':
    sys.exit(Main())
  
new_contents: #!/usr/bin/env python
  #
  # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
  # for details. All rights reserved. Use of this source code is governed by a
  # BSD-style license that can be found in the LICENSE file.
  #
  
  import shutil
  import sys
  import subprocess
  import utils
  
  def Main():
    build_root = utils.GetBuildRoot(utils.GuessOS())
    print 'Deleting %s' % build_root
    if sys.platform != 'win32':
      shutil.rmtree(build_root, ignore_errors=True)
    else:
      # Intentionally ignore return value since a directory might be in use.
      subprocess.call(['rmdir', '/Q', '/S', build_root],
                      env=os.environ.copy(),
                      shell=True)
    return 0
  
  if __name__ == '__main__':
    sys.exit(Main())
  
subject: Add missing import to utility python script