my_list = [23, 11, 42, 24523]

# append will add it as if you're adding a new list to it
my_list.append([34523, 76979])
print(my_list)

# extend will go over each item in the new source list and add each
# element as part of the target list (my_list)
my_list.extend([12, 99])
print(my_list)