title: I want to add an arrow at the end of the line
body: <p>I tried this code</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;svg&gt;
  &lt;g id="vc"&gt;
  &lt;defs&gt;
      &lt;marker id="arrowhead_bc" markerWidth="10" markerHeight="7" 
      refX="0" refY="3.5"&gt;
        &lt;polygon points="0 0, 10 3.5, 0 7" /&gt;
      &lt;/marker&gt;
    &lt;/defs&gt;
    &lt;rect x='.5' y='0' width='120' height='.5' style="fill:red;stroke:red" marker-end="url(arrowhead_bc)"/&gt;
  &lt;/g&gt;
  &lt;/svg&gt;</code></pre>
  </div>
  </div>
  </p>
  <p>I want to add an arrow at the end of the line with angle position so that I can use a rect element?</p>