I am running my code, below.
I get the following error on the console window,
Traceback (most recent call last):
File "python", line 10, in
File "python", line 7, in flatten
TypeError: can only concatenate list (not "int") to list
n = [[1, 2, 3], [4, 5, 6, 7, 8, 9]] # Add your function here def flatten(lists): results =  for numbers in lists: for i in numbers: results = results + i return results print flatten(n) What is wrong with my code? Please help.