add list as element in array

numbers = [100,200,250,300]
numbers.append([101,201,251,301])
print len(numbers)

Here is what the above code is Doing:
1. We create a list called numbers.
2. We add 4 items to the list.
3. We add another list to the list.
4. We print the length of the list.

The output of the above code is 5.

The reason for this is that the list we added to the list is considered one item.

If we wanted to add the items in the list to the original list, we could use the extend method.