ndpar_new()
instantiates a newndpar
node.ndpar_type()
checks if the node is andpar
node.ndpar_<child>_get()
returns the<child>
node ofndpar
.ndpar_<child>_set()
sets the new<child>
and deletes the old<child>
.ndpar_<child>_rep()
sets the new<child>
and returns the old<child>
.