d data from a data stream opened for reading"""</span>
        <span class="k">with</span> <span class="bp">self</span><span class="o">.</span><span class="n">_stream_lock</span><span class="p">:</span>
            <span class="k">if</span> <span class="ow">not</span> <span class="n">name</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">_streams</span><span class="p">:</span>
                <span class="k">raise</span> <span class="ne">Exception</span><s