def node_def_add_node(sss):
  """ add node{} to a string of an op.

  Args:
    sss: original string of an op.

  Returns:
    new string with node{} added.
  """
  sss = sss.replace('\n', '\n\t')
  sss = "node {\n\t" + sss
  sss = sss[0:len(sss)-1] + '}\n'
  return sss