="computeroutput"><span class="identifier">_val</span></code>, the
              rule's synthesized attribute, to zero before anything else. The actual
              parser starts at <code class="computeroutput"><span class="special">+</span><span class="identifier">lit</span><span class="special">(</span><span class="char">'M'</span><span class="special">)</span></code>,
              parsing roman thousands. Using <code class="computeroutput"><span class="identifier">eps</span></code>
              this w