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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 preload_pages():
 """Register all pages before the first application request."""

    try:
        _add_url_rule([page.url for page in Page.query.all()])
    except Exception:  # pragma: no cover
        current_app.logger.warn('Pages were not loaded.')
        raise