}
	c := b.buf[b.r]
	b.r++
	b.lastByte = int(c)
	return c, nil
}

// UnreadByte unreads the last byte. Only the most recently read byte can be unread.
//
// UnreadByte returns an error if the most recent method called on the
// [Reader] was not a read operation. Notably, [Reader.Peek], [Reader.Discard], and [Reader.WriteTo] are not
// considered read operations.
func (b *Reader) UnreadByte() error {

<p>
The exit of a goroutine is not guaranteed to be synchronized before
any event in the program.
For example, in this program:
</p>

<pre>
var a string

func hello() {
	go func() { a = "hello" }()
	print(a)
}
</pre>

<p>
the assignment to <code>a</code> is not followed by
any synchronization event, so it is not guaranteed to be
observed by any other goroutine.

pkg debug/elf, const R_390_TLS_IE32 = 47
pkg debug/elf, const R_390_TLS_IE32 R_390
pkg debug/elf, const R_390_TLS_IE64 = 48
pkg debug/elf, const R_390_TLS_IE64 R_390
pkg debug/elf, const R_390_TLS_IEENT = 49
pkg debug/elf, const R_390_TLS_IEENT R_390
pkg debug/elf, const R_390_TLS_LDCALL = 39
pkg debug/elf, const R_390_TLS_LDCALL R_390
pkg debug/elf, const R_390_TLS_LDM32 = 45
pkg debug/elf, const R_390_TLS_LDM32 R_390