TypeError: Can Only Join An Iterable Python

I'm trying to insert delimiters into a string that was created by a previous function (ifw(in_list)). I'm not having any issues with \n or \t but once my code gets to ',' join it b

Solution 1:

Your ifw function has no return statement, so it returns None.

So the line:

x = ','.join(str(x) for x in (ifw(in_list)))

becomes

x = ','.join(str(x) for x in None)

and python can't iterate over None.