n, err = C.sqrt(-1)
	_, err := C.voidFunc()
	var n, err = C.sqrt(1)

Calling C function pointers is currently not supported, however you can
declare Go variables which hold C function pointers and pass them
back and forth between Go and C. C code may call function pointers
received from Go. For example:

	package main

	// typedef int (*intFunc) ();
	//
	// int
	// bridge_int_func(intFunc f)
	// {

	}
	b = b[0:n]

	// Check the resulting bytes
	if !Equal(buf.Bytes(), b) {
		t.Fatalf("incorrect result from WriteRune: %q not %q", buf.Bytes(), b)
	}

	p := make([]byte, utf8.UTFMax)
	// Read it back with ReadRune
	for r := rune(0); r < NRune; r++ {
		size := utf8.EncodeRune(p, r)
		nr, nbytes, err := buf.ReadRune()
		if nr != r || nbytes != size || err != nil {

raw string literals and interpreted string literals.
</p>

<p>
Raw string literals are character sequences between back quotes, as in
<code>`foo`</code>.  Within the quotes, any character may appear except
back quote. The value of a raw string literal is the
string composed of the uninterpreted (implicitly UTF-8-encoded) characters
between the quotes;

// A Header represents a single header in a tar archive.
// Some fields may not be populated.
//
// For forward compatibility, users that retrieve a Header from Reader.Next,
// mutate it in some ways, and then pass it back to Writer.WriteHeader
// should do so by creating a new Header and copying the fields
// that they are interested in preserving.
type Header struct {
	// Typeflag is the type of header entry.

but may nonetheless break some existing programs,
we first engineer the change to keep as many existing programs working as possible.
For the remaining programs,
we define a new GODEBUG setting that
allows individual programs to opt back in to the old behavior.
A GODEBUG setting may not be added if doing so is infeasible,
but that should be extremely rare.

GODEBUG settings added for compatibility will be maintained

When Go 1.23 builds older programs, the old behaviors remain in effect.
The new [GODEBUG setting](/doc/godebug) [`asynctimerchan=1`](/pkg/time/#NewTimer)
can be used to revert back to asynchronous channel behaviors

var errDiscardedBytes = errors.New("ReadAt of discarded bytes")

func (ss *suffixSaver) ReadAt(p []byte, off int64) (n int, err error) {
	back := ss.size - off
	if back > int64(ss.keep) {
		return 0, errDiscardedBytes
	}
	suf := ss.Suffix()
	n = copy(p, suf[len(suf)-int(back):])
	if n != len(p) {
		err = io.EOF
	}
	return
}

func (ss *suffixSaver) Suffix() []byte {
	if len(ss.buf) < ss.keep {

		if tok.ScanToken == scanner.EOF {
			p.errorf("missing right parenthesis")
			return
		}
		rname := tok.String()
		p.back()
		haveConstant = !p.atStartOfRegister(rname)
		if !haveConstant {
			p.back() // Put back the '('.
		}
	}
	if haveConstant {
		p.back()
		if p.have(scanner.Float) {
			if prefix != '$' {
				p.errorf("floating-point constant must be an immediate")
			}

	// Fast path for ASCII: look for the first ASCII non-space byte
	start := 0
	for ; start < len(s); start++ {
		c := s[start]
		if c >= utf8.RuneSelf {
			// If we run into a non-ASCII byte, fall back to the
			// slower unicode-aware method on the remaining bytes
			return TrimFunc(s[start:], unicode.IsSpace)
		}
		if asciiSpace[c] == 0 {
			break
		}
	}

raw string literals and interpreted string literals.
</p>

<p>
Raw string literals are character sequences between back quotes, as in
<code>`foo`</code>.  Within the quotes, any character may appear except
back quote. The value of a raw string literal is the
string composed of the uninterpreted (implicitly UTF-8-encoded) characters
between the quotes;