For example, a compiler must not invert the conditional in this program:
</p>

<pre>
*p = 1
if cond {
	*p = 2
}
</pre>

<p>
That is, the compiler must not rewrite the program into this one:
</p>

<pre>
*p = 2
if !cond {
	*p = 1
}
</pre>

<p>
If <code>cond</code> is false and another goroutine is reading <code>*p</code>,

                }
                file.send(reqx, rspx);
                fp += rspx.count;
                len -= rspx.count;
                off += rspx.count;
            } else {
                req.setParam(file.fid, fp, len - w, b, off, w);
                fp += rsp.count;
                len -= rsp.count;
                off += rsp.count;
                file.send(req, rsp);
            }

     * the smb URL syntax. If the second argument is <code>true</code>, then
     * bytes will be written to the end of the file rather than the beginning.
     *
     * @param file
     *            An <code>SmbFile</code> representing the file to write to
     * @param append
     *            Append to the end of file
     * @throws SmbException if an SMB error occurs
     */

    opt Tasks
        operation -->> tasks: Send background tasks
    end
    opt Raise other exception
        tasks -->> tasks: Handle exceptions in the background task code
    end
```

/// info

只會向用戶端送出「一個回應」。可能是其中一個錯誤回應，或是來自該路徑操作的回應。

一旦送出了其中一個回應，就不能再送出其他回應。

///

/// tip

                            final Smb2ReadResponse resp = th.send(request, RequestParam.NO_RETRY);
                            n = resp.getDataLength();
                        } catch (final SmbException e) {
                            if (e.getNtStatus() == 0xC0000011) { // NT_STATUS_END_OF_FILE
                                log.debug("Reached end of file", e);
                                n = -1;

    opt Tasks
        operation -->> tasks: Send background tasks
    end
    opt Raise other exception
        tasks -->> tasks: Handle exceptions in the background task code
    end
```

/// info

Only **one response** will be sent to the client. It might be one of the error responses or it will be the response from the *path operation*.

//
//	{label:} WORD[.cond] [ arg {, arg} ] (';' | '\n')
//
// It adds any labels to p.pendingLabels and returns the word, cond,
// operand list, and true. If there is an error or EOF, it returns
// ok=false.
//
// line may reuse the memory from scratch.
func (p *Parser) line(scratch [][]lex.Token) (word, cond string, operands [][]lex.Token, ok bool) {
next:
	// Skip newlines.

    opt Tasks
        operation -->> tasks: Send background tasks
    end
    opt Raise other exception
        tasks -->> tasks: Handle exceptions in the background task code
    end
```

/// info

Une **seule réponse** sera envoyée au client. Il peut s'agir d'une des réponses d'erreur ou de la réponse provenant du *chemin d'accès*.

// You should not assume that the request is complete until the client receives an End message.
//
// Header specification:
// End messages contain two headers, as follows:
// https://docs.aws.amazon.com/AmazonS3/latest/API/images/s3select-frame-diagram-end.png
//
// Payload specification:
// End messages have no payload.
var endMessage = []byte{
	0, 0, 0, 56, // total byte-length.

 * multiplexing requests. It encapsulates a stream and some protocol
 * knowledge (provided by a concrete subclass) so that connecting,
 * disconnecting, sending, and receiving can be syncronized
 * properly. Apparatus is provided to send and receive requests
 * concurrently.
 */

public abstract class Transport implements Runnable {

    /**
     * Default constructor for Transport.
     */
    public Transport() {