code: function register(handlebars) {
    handlebars.registerHelper('dynamic-include', function(templateName, context) {
      var templateFile = '_includes/' + templateName + '.hbs';
      var templateMatter = matter.read(templateFile);
      var compiledTemplate = handlebars.compile(templateMatter.content);
      var data = extend({}, context.data.root);
      Object.keys(context.hash)
              .forEach(function(key) {
                if (context.data.root[context.hash[key]]) {
                  data[key] = context.data.root[context.hash[key]];
                }
              });
      return compiledTemplate(data);
    });
  }
docs: allows a template to be included where the data supplied to the template is specified at the point of template invocation (rather than just inheriting the current data context)