Returns the wheather child parent relationship or not
this property is used when the tree is checkbox
and one can want to makes the all the child checked
on checked the parent of those child
and from all the checked childs if one child is unchecked
the parent will also unchecked
Returns true if anotherNode is a descendant of this node
if it is this node, one of this node's children, or a descendant of
one of this node's children