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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 _getAppStoreResource(self, ctx, name):
 """ Customize child lookup such that all installed offerings on the site store that this page is viewing are given an opportunity to display their own page. """

        offer = self.frontPageItem.store.findFirst(
            offering.InstalledOffering,
            offering.InstalledOffering.offeringName == unicode(name, 'ascii'))
        if offer is not None:
            pp = ixmantissa.IPublicPage(offer.application, None)
            if pp is not None:
                warn("Use the sharing system to provide public pages,"
                     " not IPublicPage",
                     category=DeprecationWarning,
                     stacklevel=2)
                return pp.getResource()
            return SharingIndex(offer.application.open(),
                                self.webViewer)
        return None