It should be TypeError not ValueError

[GreatBahram]

https://github.com/mhajiloo/persiantools/blob/a88112b5955cb8214e84467357bee61cc01242ba/persiantools/utils.py#L7

I think the message should be better than this, since we don't have string type in python. something like "string must be str, not {}".format(string.__class__.__name__)