class Nokogiri::CSS::Parser

def _reduce_40(val, _values, result)
        case val[0]
        when 'even'
          result = Node.new(:NTH, ['2','n','+','0'])
        when 'odd'
          result = Node.new(:NTH, ['2','n','+','1'])
        when 'n'
          result = Node.new(:NTH, ['1','n','+','0'])
        else
          # non-standard to support custom functions:
          # assert_xpath("//a[foo(., @href)]", @parser.parse('a:foo(@href)'))
          # assert_xpath("//a[foo(., @a, b)]", @parser.parse('a:foo(@a, b)'))
          # assert_xpath("//a[foo(., a, 10)]", @parser.parse('a:foo(a, 10)'))
          result = val
        end

    result
end