<span class="keyword">const</span> <span class="identifier">State</span> <span class="special">&amp;</span> start_state<span class="special">,</span> <span class="identifier">Time</span> start_time<span class="special">,</span> 
                                  <span class="identifier">Time</span> end_time<span class="special">,</span> <span class="identifier">Time</span> dt<span class="special">,</span> <span class="identifier">Observer</span> observer<span class="special">)</span><span class="special">;<