# 18.Using a list of lists in function

#1

<Below this line, add a link to the EXACT exercise that you are stuck at.>

<In what way does your code behave incorrectly? Include ALL error messages.>
Oops, try again. flatten([[1, 2], [3, 4]]) returned [1, 2] instead of [1, 2, 3, 4]

<What do you expect to happen instead?>
[1,2,3,4,5,6,7,8,9]

```python

Replace this line with your code.
n = [[1, 2, 3], [4, 5, 6, 7, 8, 9]]
def flatten(lists):
results = []
for numbers in lists:
for item in numbers:
results.append(item)
return results
print flatten(n)

``````<do not remove the three backticks above>

#2

The `return` statement should be outside of `for` loop.

#3

In Python indentation is VERY import.

``````n = [[1, 2, 3], [4, 5, 6, 7, 8, 9]]
def flatten(lists):
#start of FUNCTION, 4-spaces indent
results = []  # define an empty =list=
for a_list in lists:
# 1st FOR loop, an extra 4-spaces-indent
for item in a_list:
# 2nd FOR loop, an extra 4-spaces-indent
results.append(item)
# END of 2nd FOR loop
# END of 1st FOR loop
# now RETURN the =results= list
return results
#END of FUNCTION

print flatten(n)
``````

#4

Thanks for all ! You are awesome

#5

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