def find_split_sons(raw_nodes, parent_id, sub_ops_ids):
  """ Find ids of sons given a parent id.

  Args:
    raw_nodes: A json object contain all the nodes of the raw mxnet json file.
    parent_id: Id of a node.
    sub_ops_ids: Ids of all ops in a sub graph.

  Returns:
    Ids of sons of the specified parent.
  """
  split_ids = set()
  if raw_nodes[parent_id]["op"] != "SliceChannel":
    return split_ids
  for op_id in sub_ops_ids:
    for lst in raw_nodes[op_id]["inputs"]:
      if lst[0] == parent_id:
        split_ids.add(lst[1])
  split_ids_list = list(split_ids)
  split_ids_list.sort()
  return split_ids_list