Convert obj to unicode (if it can be be converted)

    from http://farmdev.com/talks/unicode/

def to_unicode(obj, encoding='utf-8'):
    """Convert obj to unicode (if it can be be converted)

    from http://farmdev.com/talks/unicode/"""
    if isinstance(obj, basestring):
        if not isinstance(obj, unicode):
            obj = unicode(obj, encoding)
    return obj