code: function renderPattern(pattern, data, partials) {
      var renderedHTML;
      var compiled;
  
      try {
        compiled = partialRegistry[pattern.patternPartial];
      } catch (e) {
        console.log(`Error looking up underscore template ${pattern.patternName}:`, pattern.extendedTemplate, e);
      }
  
      // This try-catch is necessary because references to undefined variables
      // in underscore templates are eval()ed directly as javascript, and as
      // such will throw very real exceptions that will shatter the whole build
      // process if we don't handle them.
      try {
        renderedHTML = compiled(_.extend(data || {}, {
          _allData: data,
          _partials: partials
        }));
      } catch (e) {
        var errorMessage = `Error rendering underscore pattern "${pattern.patternName}" (${pattern.relPath}): [${e.toString()}]`;
        console.log(errorMessage);
        renderedHTML = `${errorStyling} <div class="plError">
  <h1>Error rendering underscore pattern "${pattern.patternName}"</h1>
  <dl>
    <dt>Message</dt><dd>${e.toString()}</dd>
    <dt>Partial name</dt><dd>${pattern.patternName}</dd>
    <dt>Template path</dt><dd>${pattern.relPath}</dd>
  </dl>
  </div>
  `;
      }
  
      return renderedHTML;
    }
docs: render it