NameError: global name unicode is not defined – in Python 3

Python 3 renamed the unicode type to str, the old str type has been replaced by bytes.

if isinstance(unicode_or_str, str):
    text = unicode_or_str
    decoded = False
else:
    text = unicode_or_str.decode(encoding)
    decoded = True

You may want to read the Python 3 porting HOWTO for more such details. There is also Lennart Regebros Porting to Python 3: An in-depth guide, free online.

Last but not least, you could just try to use the 2to3 tool to see how that translates the code for you.

If you need to have the script keep working on python2 and 3 as I did, this might help someone

import sys
if sys.version_info[0] >= 3:
    unicode = str

and can then just do for example

foo = unicode.lower(foo)

You can use the six library to support both Python 2 and 3:

import six
if isinstance(value, six.string_types):
    handle_string(value)