// find the next sibling with the given tag
public data_node get_next_sibling(string name)
{
return(m_next != null?m_next.get_sibling(name) : null);
}
// find the first child with the given tag
public data_node get_child(string name)
{
return(m_first_child != null?m_first_child.get_sibling(name) : null);
}