<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def command_u2k(string, vargs):
 """ Print the Kirshenbaum ASCII string corresponding to the given Unicode IPA string. :param str string: the string to act upon :param dict vargs: the command line arguments """

    try:
        l = KirshenbaumMapper().map_unicode_string(
            unicode_string=string,
            ignore=vargs["ignore"],
            single_char_parsing=vargs["single_char_parsing"],
            return_as_list=True
        )
        print(vargs["separator"].join(l))
    except ValueError as exc:
        print_error(str(exc))