class Nokogiri::CSS::Parser

def _reduce_48(val, _values, result) 

def _reduce_48(val, _values, result)
               # n+3, -n+3
      if val[0] == 'n'
        val.unshift("1")
        result = Node.new(:NTH, val)
      elsif val[0] == '-n'
        val[0] = 'n'
        val.unshift("-1")
        result = Node.new(:NTH, val)
      else
        raise Racc::ParseError, "parse error on IDENT '#{val[1]}'"
      end

    result
end