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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 _update_application_request(app_metadata, application_id):
 """ Construct the request body to update application. :param app_metadata: Object containing app metadata :type app_metadata: ApplicationMetadata :param application_id: The Amazon Resource Name (ARN) of the application :type application_id: str :return: SAR UpdateApplication request body :rtype: dict """

    request = {
        'ApplicationId': application_id,
        'Author': app_metadata.author,
        'Description': app_metadata.description,
        'HomePageUrl': app_metadata.home_page_url,
        'Labels': app_metadata.labels,
        'ReadmeUrl': app_metadata.readme_url
    }
    return {k: v for k, v in request.items() if v}