code: func ComparePDFs(rdr1, rdr2 io.Reader, printDiff bool) (err error) {
  	var b1, b2 *bytes.Buffer
  	_, err = b1.ReadFrom(rdr1)
  	if err == nil {
  		_, err = b2.ReadFrom(rdr2)
  		if err == nil {
  			err = CompareBytes(b1.Bytes(), b2.Bytes(), printDiff)
  		}
  	}
  	return
  }
docs: // ComparePDFs reads and compares the full contents of the two specified
  // readers byte-for-byte. Nil is returned if the buffers are equal, otherwise
  // an error.