def p_ports(self, p):
        'ports : ports COMMA portname'
        wid = None
        port = Port(name=p[3], width=wid, type=None, lineno=p.lineno(1))
        p[0] = p[1] + (port,)
        p.set_lineno(0, p.lineno(1))
ports : ports COMMA portname