code: def render(self, template_name, block, **context):
          
          template = self._get_template(template_name)
          return self._render_context(template,
                                      template.blocks[block],
                                      **context)
docs: TO render a block in the template
          :param template_name: the template file name
          :param block: the name of the block within {% block $block_name %}
          :param context: **kwargs context to render
          :returns string: of rendered content