code: function renderTemplate(template, locals, cb) {
      var res;
  
      try {
        var localTemplateOptions = self.getLocalTemplateOptions(locals);
        var localsClone = _.extend({}, locals);
        self.updateLocalTemplateOptions(localsClone, undefined);
        res = template(localsClone, _.merge({}, self._options.templateOptions, localTemplateOptions));
      } catch (err) {
        if (err.message) {
          err.message = '[' + template.__filename + '] ' + err.message;
        } else if (typeof err === 'string') {
          return cb('[' + template.__filename + '] ' + err, null);
        }
        return cb(err, null);
      }
      cb(null, res);
    }
docs: Renders `template` with given `locals` and calls `cb` with the
  resulting HTML string.
  
  @param template
  @param locals
  @param cb