Render the plot using a template.

        Once the plot is complete, it needs to be rendered.  Artist uses
        the Jinja2 templating engine.  The default template results in a
        LaTeX file which can be included in your document.

        :param template: a user-supplied template or None.
        :type template: string or None.
        :returns: the rendered template as string.

        This is a very minimal implementation.  Override this method to
        include variables in the template.render call.

def render(self, template=None):
        """Render the plot using a template.

        Once the plot is complete, it needs to be rendered.  Artist uses
        the Jinja2 templating engine.  The default template results in a
        LaTeX file which can be included in your document.

        :param template: a user-supplied template or None.
        :type template: string or None.
        :returns: the rendered template as string.

        This is a very minimal implementation.  Override this method to
        include variables in the template.render call.

        """
        if not template:
            template = self.template

        response = template.render()
        return response