code: def to_unicode(s):
      
      if not isinstance(s, six.string_types):
          raise ValueError("{} must be str or unicode.".format(s))
      if not isinstance(s, six.text_type):
          s = six.text_type(s, 'utf-8')
      return s
docs: Return the object as unicode (only matters for Python 2.x).
  
      If s is already Unicode, return s as is.
      Otherwise, assume that s is UTF-8 encoded, and convert to Unicode.
  
      :param (basestring) s: a str, unicode or other basestring object
      :return (unicode): the object as unicode