if err := b.UnreadByte(); err == nil {
		t.Fatal("UnreadByte after ReadByte at EOF: got no error")
	}

	// check not at EOF
	b.WriteString("abcdefghijklmnopqrstuvwxyz")

	// after unsuccessful read
	if n, err := b.Read(nil); n != 0 || err != nil {
		t.Fatalf("Read(nil) = %d,%v; want 0,nil", n, err)
	}
	if err := b.UnreadByte(); err == nil {
		t.Fatal("UnreadByte after Read(nil): got no error")
	}

	{"[X0]", "register list: expected '-' after `[X0`, found ']'"},
	{"[X0-]", "register list: bad high register in `[X0-]`"},
	{"[X0-x]", "register list: bad high register in `[X0-x`"},
	{"[X0-X1-X2]", "register list: expected ']' after `[X0-X1`, found '-'"},
	{"[X0,X3]", "register list: expected '-' after `[X0`, found ','"},
	{"[X0,X1,X2,X3]", "register list: expected '-' after `[X0`, found ','"},

	extern GoInt64 MyFunction(int arg1, int arg2, GoString arg3);
	extern struct MyFunction2_return MyFunction2(int arg1, int arg2, GoString arg3);

found in the _cgo_export.h generated header, after any preambles
copied from the cgo input files. Functions with multiple
return values are mapped to functions returning a struct.

Not all Go types can be mapped to C types in a useful way.

	tok := in.Stack.Next()
	if tok != '\n' {
		in.expectText("expected newline after", directive)
	}
}

func (in *Input) Next() ScanToken {
	if in.peek {
		in.peek = false
		tok := in.peekToken
		in.text = in.peekText
		return tok
	}
	// If we cannot generate a token after 100 macro invocations, we're in trouble.
	// The usual case is caught by Push, below, but be safe.

//
// Buffer panics if it is called after scanning has started.
func (s *Scanner) Buffer(buf []byte, max int) {
	if s.scanCalled {
		panic("Buffer called after Scan")
	}
	s.buf = buf[0:cap(buf)]
	s.maxTokenSize = max
}

// Split sets the split function for the [Scanner].
// The default split function is [ScanLines].
//
// Split panics if it is called after scanning has started.

	fmt.Println(bytes.Count([]byte("five"), []byte(""))) // before & after each rune
	// Output:
	// 3
	// 5
}

func ExampleCut() {
	show := func(s, sep string) {
		before, after, found := bytes.Cut([]byte(s), []byte(sep))
		fmt.Printf("Cut(%q, %q) = %q, %q, %v\n", s, sep, before, after, found)
	}
	show("Gopher", "Go")
	show("Gopher", "ph")
	show("Gopher", "er")

func SplitN(s, sep []byte, n int) [][]byte { return genSplit(s, sep, 0, n) }

// SplitAfterN slices s into subslices after each instance of sep and
// returns a slice of those subslices.
// If sep is empty, SplitAfterN splits after each UTF-8 sequence.
// The count determines the number of subslices to return:
//
//	n > 0: at most n subslices; the last subslice will be the unsplit remainder.

	}
	// Restore b.off and len(b.buf).
	b.off = 0
	b.buf = b.buf[:m+n]
	return m
}

// Grow grows the buffer's capacity, if necessary, to guarantee space for
// another n bytes. After Grow(n), at least n bytes can be written to the
// buffer without another allocation.
// If n is negative, Grow will panic.
// If the buffer can't grow it will panic with [ErrTooLarge].
func (b *Buffer) Grow(n int) {

		p.errorf("register list: expected '-' after `[%s`, found %s", loName, tok)
		return
	}
	hiName := p.next().String()
	hi, ok := p.arch.Register[hiName]
	if !ok {
		p.errorf("register list: bad high register in `[%s-%s`", loName, hiName)
		return
	}
	if tok := p.next().ScanToken; tok != ']' {
		p.errorf("register list: expected ']' after `[%s-%s`, found %s", loName, hiName, tok)
	}

// The close built-in function closes a channel, which must be either
// bidirectional or send-only. It should be executed only by the sender,
// never the receiver, and has the effect of shutting down the channel after
// the last sent value is received. After the last value has been received
// from a closed channel c, any receive from c will succeed without
// blocking, returning the zero value for the channel element. The form
//
//	x, ok := <-c
//