<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def render_to_file(self, filename, **kwargs):
 """Render the graph, and write it to filename"""

        with io.open(filename, 'w', encoding='utf-8') as f:
            f.write(self.render(is_unicode=True, **kwargs))