docs: def hash_file(tar_filename):
      """hash the file"""
      hasher = sha1()
      with open(tar_filename, 'rb') as afile:
          buf = afile.read(BLOCKSIZE)
          while len(buf) > 0:
              hasher.update(buf)
              buf = afile.read(BLOCKSIZE)
      data = HASHTMPL % (hasher.hexdigest(), os.path.basename(tar_filename))
      create_file('%s.sha1' % tar_filename, data)