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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 _gen_success_message(publish_output):
 """ Generate detailed success message for published applications. Parameters publish_output : dict Output from serverlessrepo publish_application Returns ------- str Detailed success message """

    application_id = publish_output.get('application_id')
    details = json.dumps(publish_output.get('details'), indent=2)

    if CREATE_APPLICATION in publish_output.get('actions'):
        return "Created new application with the following metadata:\n{}".format(details)

    return 'The following metadata of application "{}" has been updated:\n{}'.format(application_id, details)