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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:
 def singlehtml_sidebars(app):
 """When using a ``singlehtml`` builder, replace the ``html_sidebars`` config with ``singlehtml_sidebars``. This can be used to change what sidebars are rendered for the single page called ``"index"`` by the builder. """

    if app.config.singlehtml_sidebars is not None and isinstance(
        app.builder, SingleFileHTMLBuilder
    ):
        app.config.html_sidebars = app.config.singlehtml_sidebars