void send_face_list(WebsocketsClient &client)
{
  client.send("delete_faces"); // tell browser to delete all faces
  face_id_node *head = st_face_list.head;
  char add_face[64];
  for (int i = 0; i < st_face_list.count; i++) // loop current faces
  {
    sprintf(add_face, "listface:%s", head->id_name);
    Serial.println(add_face);
    client.send("listface:anonymous"); //send face to browser
    head = head->next;
  }
}