six_strings.py

from __future__ import absolute_import, print_function, unicode_literals

from six import string_types, text_type, binary_type

## Python 2 only

some_value = 20

value_as_string = unicode(some_value)
value_as_bytes = str(some_value)

isinstance(value_as_string, basestring)

## Using six, this becomes

some_value = 20

value_as_string = text_type(some_value)
value_as_bytes = binary_type(some_value)

isinstance(value_as_string, string_types)