code: async def render_template_string(source: str, **context: Any) -> str:
      
      await current_app.update_template_context(context)
      template = current_app.jinja_env.from_string(source)
      return await _render(template, context)
docs: Render the template source with the context given.
  
      Arguments:
          source: The template source code.
          context: The variables to pass to the template.