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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 async def render_template_string(source: str, **context: Any) -> str: """Render the template source with the context given. Arguments: source: The template source code. context: The variables to pass to the template. """

    await current_app.update_template_context(context)
    template = current_app.jinja_env.from_string(source)
    return await _render(template, context)