Fixed Inconsistent return statements

[GeneCodeSavvy]

#433 Refactored the code to comply with Pylint's recommendation.

if lines_type is bytes:
   # rdflib 5
   return b'\n'.join(lines) + b'\n'
elif lines_type is str:
   # rdflib 6
   return '\n'.join(lines) + '\n'

if lines_type is bytes:
   # rdflib 5
   return b'\n'.join(lines) + b'\n'
elif lines_type is str :
   # rdflib 6
   return '\n'.join(lines) + '\n'
else:
    return ''

[tcmitchell]

Instead of returning an empty string I think this should be an error and we should raise an exception. Maybe a ValueError exception could be raised because lines is neither a bytes or a str.

[GeneCodeSavvy]

Okay. I've replaced the return empty string with raise ValueError('Lines must be either bytes or str')

[GeneCodeSavvy]

I had to add changes corresponding to no-else-return to this PR, because the changes would have caused conflicts they were separate PRs.

[tcmitchell]

Unfortunately the combination of no-else-return along with inconsistent-return is very confusing. It would have been better to do one, then branch off of that to do another. I need to take a more detailed look at these changes. Please don't make any changes. It will take me some time to review.

[GeneCodeSavvy]

I apologize, I will keep your recommendation in mind in future