usage of basestring in add_unique_check leads to a NameError Exception in py3

[ramanduh]

 def add_unique_check(self, key,
                        code=UNIQUE_CHECK_FAILED,
                        message=MESSAGES[UNIQUE_CHECK_FAILED]):
        """
            Add a unique check on a single column or combination of columns.
    
            Arguments
            ---------
    
            `key` - a single field name (string) specifying a field in which all
            values are expected to be unique, or a sequence of field names (tuple
            or list of strings) specifying a compound key
    
            `code` - problem code to report if a record is not valid, defaults to
            `UNIQUE_CHECK_FAILED`
    
            `message` - problem message to report if a record is not valid
    
            """
    
>       if isinstance(key, basestring):
E       NameError: name 'basestring' is not defined

[vatechie]

Hi, Are we expecting to close this issue as python3 has removed basestring support.