Is there a dict.update(sub_dict) function for list in Python? : Suppose a list in Python -> mylist:

mylist = [["X","Y",12], ["A","B",23]]

I want to add another sub-list of elements like:

mylist = [["X","Y",12], ["A","B",23], ["L","M",56]]

Is there a function like update() for list too just like for dictionary?