def mergeTwoLists(l1, l2):
    return list_node_from_iter(merge(min, map(list_node_to_iter, [l1, l2])))
def mergeKLists(lists):
    return list_node_from_iter(merge(min, map(list_node_to_iter, lists)))
def mergeTwoLists(l1,l2):
    return list_node_from_iter(merge(min, map(list_node_to_iter, [l1,l2])))
def mergeKLists(lists):
    return list_node_from_iter(merge(min, map(list_node_to_iter, lists)))