_output_stepper_tag&gt;">checked_stepper</a><span class="special">&lt;</span><span class="identifier">DenseOutStepper</span><span class="special">,</span> <span class="identifier">Checker</span><span class="special">,</span> <span class="identifier">dense_output_stepper_tag</span><span class="special">&gt;</span><span class="special">;</span>

      <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Observer<span class="special">,</span> <span class="