Changed parameter input in Initial Solution to program_input.

No, input is definitely a reserved keyword. It's just that python does not raise any error if you want to override the value, but that's still a very bad habit.

$ python 
Python 2.7.13 (default, Jan 12 2017, 17:59:37) 
[GCC 6.3.1 20161221 (Red Hat 6.3.1-1)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> input
<built-in function input>
>>> input = 10
>>> input
10

$ python2
Python 2.7.12 (v2.7.12:d33e0cf91556, Jun 26 2016, 12:10:39) 
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> input = 10
>>> ^D
$ python3
Python 3.5.2 (v3.5.2:4def2a2901a5, Jun 26 2016, 10:47:25) 
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> input = 10
>>> ^D

Afaik input is no longer a reserved keyword in python
it may have been when you commented though.