If you ever have multiple lists in Python that you want to combine in one list, don't panic. Python actually makes it really easy to perform a function like this. You can combine and concatenate lists just by using the plus (+) symbol -- seriously, it doesn't get much easier than that. If you want to get a better idea for how merging lists works, check out the example below.

Let's say we have two lists, and they're defined as such:

listone = [9, 13, 16]
 listtwo = [21, 36, 54]

And now let's say we want to merge the lists together to create one list. Here's how that can be done:

newlist = listone + listtwo
 print newlist

The output of the code above would be: 9, 13, 16, 21, 36, 54. And the new list, of course, would be defined like this: newlist = [9, 13, 16, 21, 36, 54]. It's that easy to combine two lists to create a new one.

To Practice: Try this interactive course on the basics of Lists, Functions, Packages and NumPy in Python.