Resolves issue #712

[Elhossein]

Added an if statement to check if str_value is not a string

Previously, the code only checked for None as a string. Now it checks for None as a NoneType by making sure str_value is a str type. This could've been implemented by
if str_value == None:
return 0
However, checking that str_value is not a string covers more cases.

[reidsunderland]

I changed the base branch to v03_wip. But it looks good to me. Thank you @Elhossein