First pass at ack.py, doesn't work, many many questions about assignment

My output looks like this:
1
1
1
1
1
1
1
Only positive values are allowed.
None
1
Only positive values are allowed.
None
Only positive values are allowed.
None
1
Only positive values are allowed.
None
Only positive values are allowed.
None
Only positive values are allowed.
None
1
Only positive values are allowed.
None
Only positive values are allowed.
None
Only positive values are allowed.
None
Only positive values are allowed.
None