Callback script error

[Dirty_Biscuit]

Hello everyone,

I'm new to python and perhaps learning it in combination with Houdini may not be the perfect way to go for a newbie but here I am.
So I get this error when trying to execute my code from a button:

Traceback (most recent call last):
File "Sop/STEGG_TEST/bt_execute", line 1, in <module>
File "Sop/STEGG_TEST, PythonModule", line 135, in main
File "Sop/STEGG_TEST, PythonModule", line 98, in encode
File "Sop/STEGG_TEST, PythonModule", line 71, in encode_enc
File "Sop/STEGG_TEST, PythonModule", line 31, in modPix
AttributeError: 'iterator' object has no attribute '__next__'

 

I'm not sure what this error means. I tried running the code outside Houdini, and the only difference was that as a standalone, it's not getting the input from the input fields I have in the UI so I had to type them myself. The rest all worked fine.

I'm not exactly sure how to go about this, should I upload the code I'm trying to run, as well as a version of the HDA I'm trying to make? 
I'm mainly interested in what this error means and why it only pops up in Houdini but not when I run externally.