ns valid until the completion handler is called.
                  </p>
                </td>
</tr>
<tr>
<td>
                  <p>
                    <code class="computeroutput"><span class="identifier">handler</span></code>
                  </p>
                </td>
<td>
                  <p>
                    The handler to be called when the write operation completes.
                    Copies will be made of the handler as required. The function
                    signature of the handler must 