def __init__(self, val, next_node=None):
        """
        :param val: Value of node
        :param next_node: Next node
        """
        self.val = val
        self.next_node = next_node
def __init__ ( self , val , next_node = None ) : self . val = val self . next_node = next_node
:param val: Value of node
        :param next_node: Next node