func (b *Buffer) SetByte(index int32, value byte) {
	b.v[b.start+index] = value
}
SetByte sets the byte value at index.
package buf
import (
	"io"
)
type Supplier func([]byte) (int, error)
type Buffer struct {
	v []byte
	start int32
	end   int32
}
func (b *Buffer) Release() {
	if b == nil || b.v == nil {
		return
	}
	freeBytes(b.v)
	b.v = nil
	b.start = 0
	b.end = 0
}
func (b *Buffer) Clear() {
	b.start = 0
	b.end = 0
}
func (b *Buffer) AppendBytes(bytes ...byte) (int, error) {
	return b.Write(bytes)
}
func (b *Buffer) AppendSupplier(writer Supplier) error {
	nBytes, err := writer(b.v[b.end:])
	b.end += int32(nBytes)
	return err
}
func (b *Buffer) Byte(index int32) byte {
	return b.v[b.start+index]
}