def height(self):
        """
        Number of edges on the longest path to a leaf `Node`.

        >>> from anytree import Node
        >>> udo = Node("Udo")
        >>> marc = Node("Marc", parent=udo)
        >>> lian = Node("Lian", parent=marc)
        >>> udo.height
        2
        >>> marc.height
        1
        >>> lian.height
        0
        """
        if self.__children_:
            return max([child.height for child in self.__children_]) + 1
        else:
            return 0