Welcome to the Treehouse Community

The Treehouse Community is a meeting place for developers, designers, and programmers of all backgrounds and skill levels to get support. Collaborate here on code errors or bugs that you need feedback on, or asking for an extra set of eyes on your latest project. Join thousands of Treehouse students and alumni in the community today. (Note: Only Treehouse students can comment or ask questions, but non-students are welcome to browse our conversations.)

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today.

Python

Lists and the Append() function in Python

What is the meaning of 'None' when appending one list object to another list object?

>>> list_one = ["abc", "def", "ghi"]
>>> list_two = ["jkl", "mno", "pqr"]
>>> print(list_one.append(list_two))
None

>>> print(list_one)
['abc', 'def', 'ghi', ['jkl', 'mno', 'pqr']]

1 Answer

Sean Pomerantz
Sean Pomerantz
1,722 Points

The function .append() simply adds an item to the end of a list and does not return a value. A function that does not return a value returns "None".

Nikolai Montesclaros
Nikolai Montesclaros
11,928 Points

Sean is correct and to just to expand, its really the print statement that is returning None and has nothing to do with appending to your list.