new_contents: import sys
  import hashlib
  
  FILE_BUFFER_SIZE = 4096
  
  
  def get_digest(file_path, digest_func='md5'):
      digester = getattr(hashlib, digest_func, None)
      if digester is None:
          raise ValueError('Unknow digest method: ' + digest_func)
  
      h = digester()
      with open(file_path, 'rb') as f:
          while True:
              buffer_ = f.read(FILE_BUFFER_SIZE)
              if buffer_ == '':
                  break
              h.update(buffer_)
      return h.hexdigest()
  
  if __name__ == "__main__":
      file_path = sys.argv[1]
      print 'Digest of %s = %s' % (file_path, get_digest(file_path))
  
  
subject: Add utility script to get a file's digest, useful for debugging purpose