list accumulator

You can accumulate lists, just like numbers and strings! This is useful if you have two lists that you want to combine into a new list:

>>> L = []
>>> newlist = ["A","B","C"]
>>> L = L + newlist
>>> print(L)
['A', 'B', 'C']
>>> newlist = ["D","E","F"]
>>> L = L + newlist
>>> print(L)
['A', 'B', 'C', 'D', 'E', 'F']

If you want, you can also use the extend method for lists which mutates the list and extends it by adding the other list to the end. Here's an example:

>>> L = []
>>> newlist = ["A","B","C"]
>>> L.extend(newlist)
>>> print(L)
['A', 'B', 'C']
>>> newlist = ["D","E","F"]
>>> L.extend(newlist)
>>> print(L)
['A', 'B', 'C', 'D', 'E', 'F']

appending to a list

There's also an append() method for lists, to add just one item to a list. Here's an example:

>>> L = []
>>> L.append("A")
>>> print(L)
['A']
>>> L.append("B")
>>> print(L)
['A', 'B']
>>> L.append("hello")
>>> print(L)
['A', 'B', 'hello']