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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 main(argv=None):
 """ben-csv entry point"""

    arguments = cli_common(__doc__, argv=argv)
    csv_export = CSVExporter(arguments['CAMPAIGN-DIR'], arguments['--output'])
    if arguments['--peek']:
        csv_export.peek()
    else:
        fieldsstr = arguments.get('--fields')
        fields = fieldsstr.split(',') if fieldsstr else None
        csv_export.export(fields)
    if argv is not None:
        return csv_export