code: 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)f 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))
docs: ports : ports COMMA portname