): Parser<T> = {
    val mark = currentPosition
    when (val lr = left()) {
        is ParserResult.Failure -> {
            restore(mark)
            right().map(r)
        }

        is ParserResult.Success -> {
            lr.map(l)
        }
    }
}


internal
fun <T> optional(parser: Parser<T>): Parser<T?> = {
    val mark = currentPosition
    when (val r = parser()) {

        result.failed(failure)

        when:
        result.result

        then:
        def e = thrown(RuntimeException)
        e == failure
    }

    def "can mark as failed after resolved"() {
        given:
        def failure = new RuntimeException()
        result.resolved("result")
        result.failed(failure)

        expect:
        result.hasResult()

	if c.cache == 0 {
		return 0, 0
	}
	if npages == 1 {
		i := uintptr(sys.TrailingZeros64(c.cache))
		scav := (c.scav >> i) & 1
		c.cache &^= 1 << i // set bit to mark in-use
		c.scav &^= 1 << i  // clear bit to mark unscavenged
		return c.base + i*pageSize, uintptr(scav) * pageSize
	}
	return c.allocN(npages)
}

// allocN is a helper which attempts to allocate npages worth of pages

				q.To.Reg = REGSP
				q.To.Offset = 0
			} else if c.cursym.Func().Text.Mark&LEAF == 0 {
				// A very few functions that do not return to their caller
				// (e.g. gogo) are not identified as leaves but still have
				// no frame.
				c.cursym.Func().Text.Mark |= LEAF
			}

			if c.cursym.Func().Text.Mark&LEAF != 0 {
				c.cursym.Set(obj.AttrLeaf, true)
				break
			}

		return properties[uint8(r)]&(pLmask) != 0
	}
	return isExcludingLatin(Letter, r)
}

// IsMark reports whether the rune is a mark character (category [M]).
func IsMark(r rune) bool {
	// There are no mark characters in Latin-1.
	return isExcludingLatin(Mark, r)
}

// IsNumber reports whether the rune is a number (category [N]).
func IsNumber(r rune) bool {
	if uint32(r) <= MaxLatin1 {

			work.nBSSRoots = nBSSRoots
		}
	}

	// Scan span roots for finalizer specials.
	//
	// We depend on addfinalizer to mark objects that get
	// finalizers after root marking.
	//
	// We're going to scan the whole heap (that was available at the time the
	// mark phase started, i.e. markArenas) for in-use spans which have specials.
	//
	// Break up the work into arenas, and further into chunks.
	//

  direction: ltr;
  display: inline-block;
}

a.external-link::after {
  /* \00A0 is a non-breaking space
        to make the mark be on the same line as the link
    */
  content: "\00A0[↪]";
}

a.internal-link::after {
  /* \00A0 is a non-breaking space
        to make the mark be on the same line as the link
    */
  content: "\00A0↪";
}

.shadow {
  box-shadow: 5px 5px 10px #999;
}

{{ define "title" }}Page Not Found{{ end }}
{{ define "content" }}
<div class="notfound">
    <div class="icon">
        <img alt="Warning" title="Uh-oh" src="/img/exclamation-mark.svg" />
    </div>

    <div class="error">
        We're sorry, the page you requested cannot be found
    </div>

    <div class="explanation">
        The URL may be misspelled
    </div>
</div>

309B          ; disallowed_STD3_mapped ; 0020 3099     # 1.1  KATAKANA-HIRAGANA VOICED SOUND MARK
309C          ; disallowed_STD3_mapped ; 0020 309A     # 1.1  KATAKANA-HIRAGANA SEMI-VOICED SOUND MARK
309D..309E    ; valid                                  # 1.1  HIRAGANA ITERATION MARK..HIRAGANA VOICED ITERATION MARK

	 */
	for p := cursym.Func().Text; p != nil; p = p.Link {
		switch p.As {
		case obj.ATEXT:
			p.Mark |= LEAF

		case ADIV, ADIVU, AMOD, AMODU:
			cursym.Func().Text.Mark &^= LEAF

		case ABL,
			ABX,
			obj.ADUFFZERO,
			obj.ADUFFCOPY:
			cursym.Func().Text.Mark &^= LEAF
		}
	}

	var q2 *obj.Prog
	for p := cursym.Func().Text; p != nil; p = p.Link {
		o := p.As