Renders the tab to HTML.

        :meth:`~horizon.tabs.Tab.get_context_data` method and
        the :meth:`~horizon.tabs.Tab.get_template_name` method are called.

        If :attr:`~horizon.tabs.Tab.preload` is ``False`` and ``force_load``
        is not ``True``, or
        either :meth:`~horizon.tabs.Tab.allowed` or
        :meth:`~horizon.tabs.Tab.enabled` returns ``False`` this method will
        return an empty string.

def render(self):
        """Renders the tab to HTML.

        :meth:`~horizon.tabs.Tab.get_context_data` method and
        the :meth:`~horizon.tabs.Tab.get_template_name` method are called.

        If :attr:`~horizon.tabs.Tab.preload` is ``False`` and ``force_load``
        is not ``True``, or
        either :meth:`~horizon.tabs.Tab.allowed` or
        :meth:`~horizon.tabs.Tab.enabled` returns ``False`` this method will
        return an empty string.
        """
        if not self.load:
            return ''
        try:
            context = self.data
        except exceptions.Http302:
            raise
        except Exception:
            exc_type, exc_value, exc_traceback = sys.exc_info()
            raise six.reraise(TemplateSyntaxError, exc_value, exc_traceback)
        return render_to_string(self.get_template_name(self.request), context)