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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 check_gcdt_update():
 """Check whether a newer gcdt is available and output a warning. """

    try:
        inst_version, latest_version = get_package_versions('gcdt')
        if inst_version < latest_version:
            log.warn('Please consider an update to gcdt version: %s' %
                                 latest_version)
    except GracefulExit:
        raise
    except Exception:
        log.warn('PyPi appears to be down - we currently can\'t check for newer gcdt versions')