code: def p_rst(p):
      
      val = p[2].eval()
  
      if val not in (0, 8, 16, 24, 32, 40, 48, 56):
          error(p.lineno(1), 'Invalid RST number %i' % val)
          p[0] = None
          return
  
      p[0] = Asm(p.lineno(1), 'RST %XH' % val)
docs: asm : RST expr