':return: Join all the values stored in this data container using the
specified separators.'

def _to_str_with_separators(self, key_val_sep, pair_sep, errors='strict'):

    lst = []
    for (key, value_list) in self.items():
        for value in value_list:
            value = smart_unicode(value, encoding=UTF8, errors=errors)
            to_app = (u'%s%s%s' % (key, key_val_sep, value))
            lst.append(to_app)
    return pair_sep.join(lst)
