Python lists append return value

Question

I wanted to create a simple binary tree as followed by this image:

basically empty , but the last values so I created the root list :

root = [list(),list()]

and made a recursive function to populate it all :

def TF(nodeT,nodeF , i):
    if i == 35 : return 'done'

    TF(nodeT.append([]),nodeT.append([]) , i = i + 1) #append T , F in the true node
    TF(nodeF.append([]),nodeT.append([]) , i = i + 1) #append T , F in the false node

my problem is simple list.append(something) in python return "None" so as soon as the function get called again (TF(None,None,1)) None.append doesnt exists.

how do I solve this? thanks in advance.

also if you have any suggestion on how to make this more efficient or in another way (never got to test my code so I am not sure on how it will do)

(my final goal is to have a True False map and an argument so : "FTFTFFFTFTF" will bring up the letter "M" etc ...)

Answer 1

In python you can use the "+" operator to contatenate two lists leaving the originals untouched. I guess that's what you want to do according to your question title. Thus

[1, 2] + [3] 

will return

[1, 2, 3]

so you can use it more in a "functional fashion". Just in case you need it

[1, 2].__add__([3])

is the equivalent to the expression before.