func (z *Reader) Reset(r io.Reader) {
	z.Header = Header{}
	z.pos = 0
	z.src = r
	z.zdata = z.zdata[:0]
	z.data = z.data[:0]
	z.idx = 0
	z.checksum.Reset()
}
func (z *Reader) Reset(r io.Reader) {
	z.Header = Header{}
	z.pos = 0
	z.src = r
	z.zdata = z.zdata[:0]
	z.data = z.data[:0]
	z.idx = 0
	z.checksum.Reset()
}
// Reset discards the Reader's state and makes it equivalent to the
// result of its original state from NewReader, but reading from r instead.
// This permits reusing a Reader rather than allocating a new one.