code: 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()
  }
docs: // 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.