Many of the tutorials have blocks of code.

In most of the cases, these blocks of code are actual complete applications that can be run as is.

In fact, those blocks of code are not written inside the Markdown, they are Python files in the `./docs_src/` directory.

And those Python files are included/injected in the documentation when generating the site.

### Docs for tests

        stack = stack.next;
      }
    }

    private static class RunnableExecutorPair {
      final Runnable runnable;
      final Executor executor;
      // Volatile because this is written on one thread and read on another with no synchronization.
      @Nullable volatile RunnableExecutorPair next;

      RunnableExecutorPair(@Nullable Runnable runnable, @Nullable Executor executor) {

  }

  /** The listeners to notify during a state transition. */
  private final ListenerCallQueue<Listener> listeners = new ListenerCallQueue<>();

  /**
   * The current state of the service. This should be written with the lock held but can be read
   * without it because it is an immutable object in a volatile field. This is desirable so that
   * methods like {@link #state}, {@link #failureCause} and notably {@link #toString} can be run

		dst = binary.LittleEndian.AppendUint32(dst, uint32(h))
	}
	return m.parent.send(m.ctx, dst)
}

// RequestStateless will send a single payload request and stream back results.
// req may not be read/written to after calling.
// TODO: Not implemented
func (m *muxClient) RequestStateless(h HandlerID, req []byte, out chan<- Response) {
	if m.init {
		out <- Response{Err: errors.New("mux client already used")}
	}

}

func (s3Select *S3Select) marshal(buf *bytes.Buffer, record sql.Record) error {
	switch s3Select.Output.format {
	case csvFormat:
		// Use bufio Writer to prevent csv.Writer from allocating a new buffer.
		bufioWriter := bufioWriterPool.Get().(*bufio.Writer)
		defer func() {
			bufioWriter.Reset(xioutil.Discard)
			bufioWriterPool.Put(bufioWriter)
		}()

		bufioWriter.Reset(buf)
		opts := sql.WriteCSVOpts{

				return
			} else if rec != nil {
				stack := debug.Stack()
				logger.Error("panic: \"%s %s\": %v\n%s", r.Method, r.URL, rec, string(stack))
				// Try to write an error response, upstream may not have written header.
				writeErrorResponse(r.Context(), w, errorCodes.ToAPIErr(ErrInternalError), r.URL)
				return
			}
		}()
		h.ServeHTTP(w, r)
	})
}

  }
  /**
   * ReadWriteLock implementation whose read and write locks retain a reference back to this lock.
   * Otherwise, a reference to just the read lock or just the write lock would not suffice to ensure
   * the {@code ReadWriteLock} is retained.
   */
  private static final class WeakSafeReadWriteLock implements ReadWriteLock {
    private final ReadWriteLock delegate;

    WeakSafeReadWriteLock() {

    /*
     * We adjust approxLog10 and approxPow until they're equal to floor(log10(x)) and
     * 10^floor(log10(x)).
     */

    if (approxCmp > 0) {
      /*
       * The code is written so that even completely incorrect approximations will still yield the
       * correct answer eventually, but in practice this branch should almost never be entered, and
       * even then the loop should not run more than once.

        added += q.drainTo(buffer, numElements - added);
        if (added < numElements) { // not enough elements immediately available; will have to poll
          E e; // written exactly once, by a successful (uninterrupted) invocation of #poll
          while (true) {
            try {
              e = q.poll(deadline - System.nanoTime(), NANOSECONDS);
              break;

   *
   * This method is always invoked after [requestBodyStart].
   */
  open fun requestBodyEnd(
    call: Call,
    byteCount: Long,
  ) {
  }

  /**
   * Invoked when a request fails to be written.
   *
   * This method is invoked after [requestHeadersStart] or [requestBodyStart]. Note that request
   * failures do not necessarily fail the entire call.
   */
  open fun requestFailed(
    call: Call,