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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 _get_serializer(output):
    '''
    Helper to return known serializer based on
    pass output argument
    '''
    serializers = salt.loader.serializers(__opts__)
    try:
        return getattr(serializers, output)
    except AttributeError:
        raise CommandExecutionError(
            "Unknown serializer '{0}' found for output option".format(output)
        )