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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 resource_to_portal_type(resource):
 """Converts a resource to a portal type :param resource: Resource name as it is used in the content route :type name: string :returns: Portal type name :rtype: string """

    if resource is None:
        return None

    resource_mapping = get_resource_mapping()
    portal_type = resource_mapping.get(resource.lower())

    if portal_type is None:
        logger.warn("Could not map the resource '{}' "
                    "to any known portal type".format(resource))

    return portal_type