Python2 and Python3 compatible "is this a unicode string" check

is_unicode.py

from __future__ import print_function

# the string to check is in 'candidate'
if isinstance(candidate, type(u"")):
    print("This is a unicode string")
else:
    # if it's a Py2 'str' or a Py3 'bytes' object, this will convert
    # otherwise it'll raise an exception
    candidate = candidate.decode('utf8')
                     
"""
In Python2, you could check ``if type(candidate) == unicode``, but that doesn't work in Py3 because
all ``str`` are unicode and there's no ``unicode`` type

So... both have ``isinstance``, so we simply compare the type to the type of an example unicode string
"""