def METHOD_NAME(topt):
    tlst = topt.split(',')
    for n in range(len(tlst)):
        t = tlst[n]
        if t[0] == '~' and t[1] != '@':
            t = '~@' + t[1:]
        elif t[0] != '~' and t[0] != '@':
            t = '@' + t
        tlst[n] = t
    return ','.join(tlst)