writer.go
func (z *Writer) writeUint32(x uint32) error {
	buf := z.buf[:4]
	binary.LittleEndian.PutUint32(buf, x)
	_, err := z.dst.Write(buf)
	return err
}
func (z *Writer) writeUint32(x uint32) error {
	buf := z.buf[:4]
	binary.LittleEndian.PutUint32(buf, x)
	_, err := z.dst.Write(buf)
	return err
}
// writeUint32 writes a uint32 to the underlying writer.